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Document And Entity Information - shares	9 Months Ended
Document And Entity Information - shares	Sep. 30, 2019	Nov. 01, 2019
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Registrant Name	SOLENO THERAPEUTICS INC
Entity Central Index Key	0001484565
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity File Number	001-36593
Entity Tax Identification Number	77-0523891
Entity Address, Address Line One	203 Redwood Shores Parkway
Entity Address, Address Line Two	Suite 500
Entity Address, City or Town	Redwood City
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94065
City Area Code	650
Local Phone Number	213-8444
Entity Common Stock Shares Outstanding		44,658,054
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Common Stock [Member]
Document Information [Line Items]
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	SLNO
Security Exchange Name	NASDAQ
Common Stock Underlying Warrants [Member]
Document Information [Line Items]
Title of 12(b) Security	Common Stock, $0.001 per value, underlying the warrants
Trading Symbol	SLNOW
Security Exchange Name	NASDAQ

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 11,225	$ 23,099
Prepaid expenses and other current assets	375	529
Due from related party	9	64
Minority interest investment in former subsidiary		978
Total current assets	11,609	24,670
Long-term assets
Property and equipment, net	46	12
Intangible assets, net	17,011	18,469
Other long-term assets	59
Total assets	28,725	43,151
Current liabilities
Accounts payable	1,735	934
Accrued compensation and other current liabilities	1,719	943
Total current liabilities	3,454	1,877
Long-term liabilities
Contingent liability for Essentialis purchase price	6,066	5,649
Other long-term liabilities	38
Total liabilities	13,840	12,738
Commitments and contingencies (Note 6)
Stockholders’ equity
Common stock	32	32
Additional paid-in-capital	158,034	157,413
Accumulated deficit	(143,181)	(127,032)
Total stockholders’ equity	14,885	30,413
Total liabilities and stockholders’ equity	28,725	43,151
Series B Convertible Preferred Stock [Member]
Stockholders’ equity
Preferred stock
Series A Warrant Liability [Member]
Long-term liabilities
Warrant liability	25	49
2017 PIPE Warrant Liability [Member]
Long-term liabilities
Warrant liability	3,667	4,563
2018 PIPE Warrant Liability [Member]
Long-term liabilities
Warrant liability	$ 590	$ 600

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Preferred stock par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock shares authorized	10,000,000	10,000,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	31,793,292	31,755,169
Common stock, shares outstanding	31,793,292	31,755,169
Series B Convertible Preferred Stock [Member]
Preferred stock par value (in dollars per share)	$ 0.001
Preferred stock shares authorized	13,780	13,780
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Preferred stock, aggregate liquidation preference	$ 0	$ 0

Condensed Consolidated Statements of Operations (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Operating expenses
Research and development	$ 4,490	$ 2,092	$ 10,995	$ 4,986
General and administrative	1,615	1,558	5,322	5,191
Change in fair value of contingent consideration	28	228	417	589
Total operating expenses	6,133	3,878	16,734	10,766
Operating loss	(6,133)	(3,878)	(16,734)	(10,766)
Other income (expense)
Cease-use income				6
Change in fair value of warrants liabilities	7,116	1,543	930	(1,549)
Loss from minority interest investment	(123)		(478)
Interest income, net	29	26	133	75
Total other income (expense)	7,022	1,569	585	(1,468)
Income (loss) from continuing operations	889	(2,309)	(16,149)	(12,234)
Loss from discontinued operations		(427)		(1,364)
Net income (loss)	$ 889	$ (2,736)	$ (16,149)	$ (13,598)
Income (loss) per common share from continuing operations:
Basic	$ 0.03	$ (0.11)	$ (0.51)	$ (0.60)
Diluted	(0.19)	(0.11)	(0.53)	(0.60)
Loss per common share from discontinued operations:
Basic		(0.02)		(0.07)
Diluted		(0.02)		(0.07)
Net income (loss) per common share:
Basic	0.03	(0.13)	(0.51)	(0.67)
Diluted	$ (0.19)	$ (0.13)	$ (0.53)	$ (0.67)
Weighted-average common shares outstanding used in per-share calculation:
Basic	31,793,292	21,432,482	31,775,590	20,443,044
Diluted	32,443,647	21,432,482	32,235,528	20,443,044

Condensed Consolidated Statements of Stockholders' Equity (unaudited) - USD ($) $ in Thousands	Total	2017 PIPE Warrant Liability [Member]	Series B Convertible Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member] Essentialis, Inc. [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] 2017 PIPE Warrant Liability [Member]	Additional Paid-In Capital [Member] Essentialis, Inc. [Member]	Accumulated Deficit [Member]
Balances at beginning at Dec. 31, 2017	$ 26,817			$ 19		$ 140,495			$ (113,697)
Balances at beginning (shares) at Dec. 31, 2017			4,571	19,238,972
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	200					200
Issuance of common stock on conversion of series B convertible preferred shares	1			$ 1
Issuance of common stock on conversion of series B convertible preferred shares (shares)			(1,000)	200,000
Issuance of restricted common stock for bonuses	159					159
Issuance of restricted common stock for bonuses (shares)				99,217
Issuance of common stock to board members in lieu of cash payments for quarterly board fees	82					82
Issuance of common stock to board members in lieu of cash payments for quarterly board fees (shares)				49,519
Transaction costs for common stock and warrant issuance.		$ (203)					$ (203)
Issuance of common stock held back on acquisition of Essentialis (Shares)					180,667
Net income (loss)	(3,804)								(3,804)
Balances at ending at Mar. 31, 2018	23,252			$ 20		140,733			(117,501)
Balances at end (shares) at Mar. 31, 2018			3,571	19,768,375
Balances at beginning at Dec. 31, 2017	26,817			$ 19		140,495			(113,697)
Balances at beginning (shares) at Dec. 31, 2017			4,571	19,238,972
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(13,598)
Balances at ending at Sep. 30, 2018	16,941			$ 21		141,479			(124,559)
Balances at end (shares) at Sep. 30, 2018				21,435,241
Balances at beginning at Mar. 31, 2018	23,252			$ 20		140,733			(117,501)
Balances at beginning (shares) at Mar. 31, 2018			3,571	19,768,375
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	199					199
Issuance of common stock on conversion of series B convertible preferred shares	(1)					(1)
Issuance of common stock on conversion of series B convertible preferred shares (shares)			(3,571)	714,200
Issuance of common stock to board members in lieu of cash payments for quarterly board fees	54					54
Issuance of common stock to board members in lieu of cash payments for quarterly board fees (shares)				27,925
Transaction costs for common stock and warrant issuance.		$ 203					$ 203
Issuance of common stock held back on acquisition of Essentialis					$ 1			$ (1)
Issuance of common stock held back on acquisition of Essentialis (Shares)					903,367
Net income (loss)	(7,058)								(7,058)
Balances at ending at Jun. 30, 2018	16,649			$ 21		141,187			(124,559)
Balances at end (shares) at Jun. 30, 2018				21,413,867
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	231					231
Issuance of common stock to board members in lieu of cash payments for quarterly board fees	61					61
Issuance of common stock to board members in lieu of cash payments for quarterly board fees (shares)				21,374
Net income (loss)	(2,736)
Balances at ending at Sep. 30, 2018	16,941			$ 21		141,479			(124,559)
Balances at end (shares) at Sep. 30, 2018				21,435,241
Balances at beginning at Dec. 31, 2018	30,413			$ 32		157,413			(127,032)
Balances at beginning (shares) at Dec. 31, 2018				31,755,169
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	202					202
Issuance of common stock to board members in lieu of cash payments for quarterly board fees	46					46
Issuance of common stock to board members in lieu of cash payments for quarterly board fees (shares)				21,415
Net income (loss)	(7,030)								(7,030)
Balances at ending at Mar. 31, 2019	23,631			$ 32		157,661			(134,062)
Balances at end (shares) at Mar. 31, 2019				31,776,584
Balances at beginning at Dec. 31, 2018	30,413			$ 32		157,413			(127,032)
Balances at beginning (shares) at Dec. 31, 2018				31,755,169
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(16,149)
Balances at ending at Sep. 30, 2019	14,885			$ 32		158,034			(143,181)
Balances at end (shares) at Sep. 30, 2019				31,793,292
Balances at beginning at Mar. 31, 2019	23,631			$ 32		157,661			(134,062)
Balances at beginning (shares) at Mar. 31, 2019				31,776,584
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	175					175
Issuance of common stock to board members in lieu of cash payments for quarterly board fees	45					45
Issuance of common stock to board members in lieu of cash payments for quarterly board fees (shares)				16,708
Net income (loss)	(10,008)								(10,008)
Balances at ending at Jun. 30, 2019	13,843			$ 32		157,881			(144,070)
Balances at end (shares) at Jun. 30, 2019				31,793,292
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	153					153
Net income (loss)	889								889
Balances at ending at Sep. 30, 2019	$ 14,885			$ 32		$ 158,034			$ (143,181)
Balances at end (shares) at Sep. 30, 2019				31,793,292

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net loss	$ (16,149)	$ (13,598)
Loss from discontinued operations		(1,364)
Loss from continuing operations	(16,149)	(12,234)
Adjustments to reconcile net loss from continuing operations to net cash used in operating activities:
Depreciation and amortization	1,468	1,473
Stock-based compensation expense	530	731
Board fees paid with common stock	91	197
Change in fair value of stock warrants	(930)	1,549
Change in fair value of contingent consideration	417	589
Operating loss on minority interest investment	478
Change in operating assets and liabilities:
Prepaid expenses and other current assets	154	142
Due from related party	55
Accounts payable	801	612
Accrued compensation and other liabilities	786	167
Net cash used in continuing operating activities	(12,299)	(6,774)
Net cash used in discontinued operating activities		(1,173)
Net cash used in operating activities	(12,299)	(7,947)
Cash flows from investing activities:
Purchases of property and equipment	(16)	(6)
Security deposit on sublease	(59)
Proceeds from sale of minority interest investment in former subsidiary	500
Net cash provided by (used in) continuing investing activities	425	(6)
Net cash provided by (used in) investing activities	425	(6)
Cash flows from financing activities:
Net cash provided by discontinued financing activities		1,525
Net cash provided by financing activities		1,525
Net decrease in cash, cash equivalents and restricted cash	(11,874)	(6,428)
Net increase in cash and cash equivalents included in current assets held for sale		(468)
Cash, cash equivalents and restricted cash, beginning of period	23,099	17,135
Cash, cash equivalents and restricted cash, end of period	11,225	10,239
Supplemental disclosure of non-cash investing and financing information
Purchases of property and equipment with capital lease obligation	28
Continuing Operations [Member]
Cash flows from financing activities:
Net decrease in cash, cash equivalents and restricted cash from continuing operations	$ (11,874)	(6,780)
Discontinued Operations
Cash flows from financing activities:
Net decrease in cash, cash equivalents and restricted cash from continuing operations		$ 352

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2019

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Note 3. Summary of Significant Accounting Policies

There have been no material changes to the significant accounting policies during the nine months ended September 30, 2019 as compared to the significant accounting policies described in Note 3 of the “Notes to Consolidated Financial Statements” in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018. Below are those policies with current period updates.

Basis of Presentation

The accompanying condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP, and the applicable rules and regulations of the SEC for interim financial information. Accordingly, they do not include all of the information and notes required by GAAP for complete financial statements. The condensed consolidated balance sheet at December 31, 2018, has been derived from the audited consolidated financial statements at that date, but does not include all disclosures, including notes, required by GAAP for complete financial statements.

The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and, in the opinion of management, reflect all adjustments of a normal recurring nature that are necessary for a fair presentation of the results for the interim periods presented. The interim results are not necessarily indicative of the results for any future interim period or for the entire year.

The accompanying condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto for the year ended December 31, 2018, included in the Company’s Annual Report on Form 10-K.

Recent Accounting Standards

Recently Adopted Accounting Standards

In June 2018, the FASB issued ASU 2018-07, “Compensation – Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting”, to simplify the accounting for share-based payments to nonemployees by aligning it with the accounting for share-based payments to employees, with certain exceptions. Under the guidance, the measurement of equity-classified nonemployee awards is fixed at the grant date, which may lower the cost and reduce volatility in the income statement. This ASU was early adopted by the Company at the beginning of 2019. Its adoption did not have a material impact on the Company’s condensed consolidated financial statements.

In August 2018, SEC adopted the final rule under SEC Release No. 33-10532, “Disclosure Update and Simplification”, amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of stockholders’ equity for interim financial statements. Under the amendments, an analysis of changes in each caption of stockholders’ equity presented in the balance sheet must now be provided in a note or separate statement. The Company has applied this new guidance to its condensed financial statements beginning in the first quarter of 2019.

Recently Issued Accounting Standards

In February 2016, the FASB issued ASU 2016-02: “Leases (Topic 842)”. ASU 2016-02 provides new comprehensive lease accounting guidance that supersedes existing lease guidance. Upon adoption of ASU 2016-02, the Company may elect to apply the transition approach either as of the beginning of the earliest period presented in the financial statements – in which case it would restate its comparative periods, or as of the beginning of the period of adoption – in which case it would not restate its comparative periods. ASU 2016-02 requires the Company to capitalize most current operating lease obligations as right-of-use assets with a corresponding liability based on the present value of future operating lease obligations. Criteria for distinguishing leases between finance and operating are substantially similar to criteria for distinguishing between capital leases and operating leases in existing lease guidance. Lease agreements that are 12 months or less are permitted to be excluded from the balance sheet. Topic 842 includes a number of optional practical expedients that the Company may elect to apply. Expanded disclosures with additional qualitative and quantitative information will also be required. The adoption will include updates as provided under ASU 2018-01, Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842, ASU 2018-10, Codification Improvements to Topic 842, Leases, ASU 2018-20, Leases (Topic 842): Narrow-Scope Improvements for Lessors and ASU 2019-01, Leases (Topic 842): Codification Improvements. Topic 842 is effective for public entities with fiscal years beginning after December 15, 2018 and for all other entities for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2020. As the Company is an emerging growth company and elected to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act, Topic 842 will be effective for the Company beginning in fiscal 2020, although early adoption is permitted. The Company will adopt the new lease standard effective beginning in the fiscal year beginning January 1, 2020 using a modified retrospective method and will not restate comparative periods. The Company currently believes that its operating lease commitments will be subject to the new standard and recognized as an operating lease liability and right-of-use asset upon the adoption of Topic 842, which will increase the Company’s total assets and total liabilities in its condensed consolidated balance sheet.

In July 2017, the FASB issued ASU 2017-11, “Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815): (Part I) Accounting for Certain Financial Instruments with Down Round Features; (Part II) Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception”, (ASU 2017-11). Part I of this update addresses the complexity of accounting for certain financial instruments with down round features. Down round features are features of certain equity-linked instruments (or embedded features) that result in the strike price being reduced on the basis of the pricing of future equity offerings. Current accounting guidance creates cost and complexity for entities that issue financial instruments (such as warrants and convertible instruments) with down round features that require fair value measurement of the entire instrument or conversion option. Part II of this update addresses the difficulty of navigating Topic 480, Distinguishing Liabilities from Equity, because of the existence of extensive pending content in the FASB Accounting Standards Codification. This pending content is the result of the indefinite deferral of accounting requirements about mandatorily redeemable financial instruments of certain nonpublic entities and certain mandatorily redeemable noncontrolling interests. The amendments in Part II of this update do not have an accounting effect. The amendments in Part I of ASU 2017-11 are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. For all other entities, the amendments in Part I are effective for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2020. As the Company is an emerging growth company and elected to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act, this ASU 2017-11 will be effective for the Company beginning in fiscal 2020, although early adoption is permitted. The Company is currently assessing the potential impact of adopting ASU 2017-11 on its condensed consolidated financial statements and related disclosures.

In August 2018, the FASB issued ASU 2018-13, “Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement”. The ASU modifies the disclosure requirements for fair value measurements by removing, modifying, or adding certain disclosures. This ASU is effective for the Company beginning in 2020. Early adoption is permitted. An entity is permitted to early adopt any removed or modified disclosures upon issuance of ASU No. 2018-13 and delay adoption of the additional disclosures until their effective date. The Company has not yet evaluated the impact of adoption of this ASU on its condensed consolidated financial statements disclosures.

Fair Value of Financial Instruments

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

Note 4. Fair Value of Financial Instruments

The carrying value of the Company’s cash, restricted cash, cash equivalents and accounts payable, approximate fair value due to the short-term nature of these items.

Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs.

The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows:

•

Level I — Unadjusted quoted prices in active markets for identical assets or liabilities;

•

Level II — Inputs other than quoted prices included within Level I that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and

•

Level III — Unobservable inputs that are supported by little or no market activity for the related assets or liabilities.

The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement.

The following table sets forth the Company’s financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands).

	Fair Value Measurements at September 30, 2019
	Total		Level 1		Level 2		Level 3
Liabilities
Series A warrant liability	$	25	$	25	$	—	$	—
2017 PIPE warrant liability		3,667		—		—		3,667
2018 PIPE warrant liability		590		—		—		590
Essentialis purchase price contingency liability		6,066		—		—		6,066
Total common stock warrant and contingent consideration liability	$	10,348	$	25	$	—	$	10,323

	Fair Value Measurements at December 31, 2018
	Total		Level 1		Level 2		Level 3
Liabilities
Series A warrant liability	$	49	$	49	$	—	$	—
2017 PIPE warrant liability		4,563		—		—		4,563
2018 PIPE warrant liability		600		—		—		600
Essentialis purchase price contingency liability		5,649		—		—		5,649
Total common stock warrant and contingent consideration liability	$	10,861	$	49	$	—	$	10,812

The Series A Warrant is a registered security that trades on the open market and the fair value of the Series A Warrant liability is based on the publicly quoted trading price of the warrants which is listed on and obtained from NASDAQ. Accordingly, the fair value of Series A Warrants is a Level 1 measurement. The fair value measurement of the Series C Warrants is based on significant inputs that are unobservable and thus represent Level 3 measurements. The Company’s estimated fair value of the Series C Warrant liability is calculated using the Black-Scholes valuation model, which is equivalent to fair value computed using the Binomial Lattice Option Model. Key assumptions include the volatility of the Company’s stock, the expected warrant term, expected dividend yield and risk-free interest rates. The Company’s estimated fair value of the 2017 PIPE Warrants and the 2018 PIPE Warrants was calculated using a Monte Carlo simulation of a geometric Brownian motion model. The Monte Carlo simulation pricing model requires the input of highly subjective assumptions including the expected stock price volatility, the expected term, the expected dividend yield and the risk-free interest rate. The fair value of the Essentialis purchase price contingent liability is estimated using scenario-based methods based upon the Company’s analysis of the likelihood of obtaining specified approvals from the Federal Drug Administration as well as reaching cumulative revenue milestones (see Note 10). The Level 3 estimates are based, in part, on subjective assumptions.

During the periods presented, the Company has not changed the manner in which it values liabilities that are measured at fair value using Level 3 inputs. The Company recognizes transfers between levels of the fair value hierarchy as of the end of the reporting period. There were no transfers within the hierarchy during the periods presented.

The following table sets forth a summary of the changes in the fair value of the Company’s Level 1 and Level 3 warrants, which are treated as liabilities (dollars in thousands).

	Series A Warrant					Series C Warrant				2017 PIPE Warrants					2018 PIPE Warrants					Purchase Price
	Number of Warrants		Liability			Number of Warrants		Liability		Number of Warrants		Liability			Number of Warrants		Liability			Contingent Liability
Balance at December 31, 2018		485,121	$	49			118,083	$	—		6,024,425	$	4,563			513,617	$	600		$	5,649
Change in value of Series A Warrants		—		(24	)		—		—		—		—			—		—			—
Change in value of 2017 PIPE Warrants		—		—			—		—		—		(896	)		—		—			—
Change in value of 2018 PIPE Warrants		—		—			—		—		—		—			—		(10	)		—
Change in value of contingent liability		—		—			—		—		—		—			—		—			417
Balance at September 30, 2019		485,121	$	25			118,083	$	—		6,024,425	$	3,667			513,617	$	590		$	6,066

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Warrant Liabilities

9 Months Ended

Sep. 30, 2019

Text Block [Abstract]

Warrant Liabilities

Note 5. Warrant Liabilities

The Company has issued multiple warrant series, of which the Series A Warrants, Series C Warrants, the 2017 PIPE Warrants and the 2018 PIPE Warrants (the “Warrants”) are considered liabilities pursuant to the guidance established by ASC 815 Derivatives and Hedging.

Accounting Treatment

The Company accounts for the Warrants in accordance with the guidance in ASC 815. As indicated below, the Company may be obligated to settle Warrants in cash in the case of a Fundamental Transaction (as defined in the Warrants).

The Company classified the Warrants, with a term greater than one year, as long-term liabilities at their fair value and will re-measure the warrants at each balance sheet date until they are exercised or expire. Any change in the fair value is recognized as other income (expense) in the Company’s condensed consolidated statements of operations.

Series A Warrants

The Company has issued 489,921 Series A Warrants to purchase shares of its common stock at an exercise price of $32.50 per share in connection with the unit offering offered in the Company’s initial public offering, or the IPO, in November 2014. The Series A Warrants are exercisable at any time prior to the expiration of the five-year term on November 12, 2019.

Upon the completion of the IPO, the Series A Warrants started trading on the NASDAQ under the symbol SLNOW. As the Series A Warrants are publicly traded, the Company uses the closing price on the measurement date to determine the fair value of the Series A Warrants. The Series A Warrants contract further provides for the payment of liquidated damages at an amount per month equal to 1% of the aggregate volume weighted average price, or VWAP, of the shares into which each Warrant is convertible in the event that the Company is unable to maintain the effectiveness of a registration statement as described herein. The Company evaluated the registration payment arrangement stipulated in the terms of these securities and determined that it is probable that the Company will maintain an effective registration statement and has therefore not allocated any portion of the proceeds related to the warrant financings to the registration payment arrangement. The Warrants also contain a fundamental transactions provision that permits their settlement in cash at fair value at the option of the holder upon the occurrence of a change in control. Such change in control events include tender offers or hostile takeovers, which are not within the sole control of the Company as the issuer of these warrants. Accordingly, the Warrants are considered to have a cash settlement feature that precludes their classification as equity instruments. Settlement at fair value upon the occurrence of a fundamental transaction would be computed using the Black Scholes Option Pricing Model, which approximates the binomial lattice model.

Since their issuance, a total of 4,800 Series A Warrants have been exercised. As of September 30, 2019, the fair value of the 485,121 outstanding Series A Warrants was approximately $25,000. The decrease of approximately $26,000 and $24,000 in fair value during the three and nine months ended September 30, 2019, respectively, was recorded as other income in the condensed consolidated statements of operations.

Series C Warrants

On March 5, 2015, the Company entered into separate agreements with certain Series B Warrant holders, who agreed to exercise their Series B Warrants to purchase an aggregate of 117,902 shares of the Company’s common stock at an exercise price of $32.50 per share, resulting in the de-recognition of $6.7 million of the previously issued Series B Warrant liability and gross proceeds to the Company of $3.8 million based on the exercise price of the Series B Warrants. In connection with this exercise of the Series B Warrants, the Company issued to each investor who exercised Series B Warrants, new Series C Warrants for the number of shares of the Company’s common stock underlying the Series B Warrants that were exercised. Each Series C Warrant is exercisable at $31.25 per share and will expire on March 5, 2020. The Series C Warrants contract further provides for the payment of liquidated damages at an amount per month equal to 1% of the aggregate volume weighted average price, or VWAP, of the shares into which each Warrant is convertible in the event that the Company is unable to maintain the effectiveness of a registration statement as described herein. The Company evaluated the registration payment arrangement stipulated in the terms of these securities and determined that it is probable that the Company will maintain an effective registration statement and has therefore not allocated any portion of the proceeds related to the warrant financings to the registration payment arrangement. The Warrants also contain a fundamental transactions provision that permits their settlement in cash at fair value at the option of the holder upon the occurrence of a change in control. Such change in control events include tender offers or hostile takeovers, which are not within the sole control of the Company as the issuer of these warrants. Accordingly, the Warrants are considered to have a cash settlement feature that precludes their classification as equity instruments. Settlement at fair value upon the occurrence of a fundamental transaction would be computed using the Black Scholes Option Pricing Model, which approximates the binomial lattice model.

In April 2015, the Company issued a tender offer to the remaining holders of Series B Warrants to induce the holders to cash exercise the outstanding Series B Warrants in exchange for new Series C Warrants with an exercise price of $31.25 per share that expire on March 5, 2020. The tender offer was extended to Series B Warrant holders under a registration statement filed with the SEC on Form S-4, which was declared effective on June 25, 2015 and expired on July 24, 2015. During July 2015, certain Series B Warrant holders tendered their Series B Warrants under the tender offer, which resulted in the issuance of 181 shares of the Company’s common stock, the issuance of 181 Series C Warrants and proceeds to the Company of approximately $6,000.

The Series C Warrants are exercisable into 118,083 shares of the Company’s common stock. As of September 30, 2019, the fair value of the Series C Warrants was determined to be zero, consistent with the balance as of December 31, 2018 and June 30, 2019.

The Company has calculated the fair value of the Series C Warrants using a Black-Scholes pricing model. The Black-Scholes pricing model requires the input of highly subjective assumptions including the expected stock price volatility. The Company used the following inputs.

	September 30, 2019			December 31, 2018
Volatility		90	%		90	%
Contractual term (years)		0.42			1.17
Expected dividend yield		—	%		—	%
Risk-free rate		1.85	%		2.60	%

Warrants Issued as Part of the Units in the 2017 PIPE Offering

The 2017 PIPE Warrants were issued on December 15, 2017 in the 2017 PIPE Offering, pursuant to a Warrant Agreement with each of the investors in the 2017 PIPE Offering, and entitle the holder to purchase one share of the Company’s common stock at an exercise price equal to $2.00 per share, subject to adjustment as discussed below, at any time commencing upon issuance of the 2017 PIPE Warrants and terminating at the earlier of December 15, 2020 or 30 days following positive Phase III results for the DCCR tablet in PWS.

The exercise price and number of shares of common stock issuable upon exercise of the 2017 PIPE Warrants may be adjusted in certain circumstances, including the event of a stock split, stock dividend, extraordinary dividend, or recapitalization, reorganization, merger or consolidation. However, the exercise price of the 2017 PIPE Warrants will not be reduced below $1.72.

In the event of a change of control of the Company, the holders of unexercised warrants may present their unexercised warrants to the Company, or its successor, to be purchased by the Company, or its successor, in an amount equal to the per share value determined by the Black Scholes methodology.

As of September 30, 2019, the fair value of the 2017 PIPE Warrants was estimated at $3.7 million. The decrease in the fair value of the liability for the 2017 PIPE Warrants of $6.5 million and approximately $896,000 during the three and nine months ended September 30, 2019, respectively, was recorded as other income in the condensed consolidated statements of operations. The decrease in the fair value of the liability for the 2017 PIPE Warrants of approximately $1.4 million during the three months ended September 30, 2018 and the increase in the fair value of $1.6 million during the nine months ended September 30, 2018, were recorded as other income and expense in the condensed consolidated statements of operations.

The Company has calculated the fair value of the 2017 PIPE Warrants using a Monte Carlo simulation of a geometric Brownian motion model. The Monte Carlo simulation pricing model requires the input of highly subjective assumptions including the expected stock price volatility. The following summarizes certain key assumptions used in estimating the fair values.

	September 30, 2019			December 31, 2018
Volatility		85	%		75	%
Contractual term (years)		1.2			2.0
Expected dividend yield		—	%		—	%
Risk-free rate		1.80	%		2.51	%

Warrants Issued as Part of the Units in the 2018 PIPE Offering

The 2018 PIPE Warrants were issued on December 19, 2018 in the 2018 PIPE Offering, pursuant to a Warrant Agreement with each of the investors in the 2018 PIPE Offering, and entitle the holders of each of the 10,272,375 units to purchase 0.05 shares of the Company’s common stock at an exercise price equal to $2.00 per share, subject to adjustment as discussed below, at any time commencing upon issuance of the 2018 PIPE Warrants and terminating on December 21, 2023.

The exercise price and number of shares of common stock issuable upon exercise of the 2018 PIPE Warrants may be adjusted in certain circumstances, including the event of a stock split, stock dividend, extraordinary dividend, or recapitalization, reorganization, merger or consolidation. However, the exercise price of the 2018 PIPE Warrants will not be reduced below $2.00.

As of September 30, 2019, the fair value of the 2018 PIPE Warrants was estimated at approximately $590,000. The approximate $555,000 and $10,000 decrease in the fair value of the liability for the 2018 PIPE Warrants during the three and nine months ended September 30, 2019, respectively, was recorded as other income in the condensed consolidated statements of operations.

The Company has calculated the fair value of the 2018 PIPE Warrants using a Monte Carlo simulation of a geometric Brownian motion model. The Monte Carlo simulation pricing model requires the input of highly subjective assumptions including the expected stock price volatility. The following summarizes certain key assumptions used in estimating the fair values.

	September 30, 2019			December 31, 2018
Volatility		85	%		75	%
Contractual term (years)		4.2			5.0
Expected dividend yield		—	%		—	%
Risk-free rate		1.56	%		2.51	%

The Monte Carlo simulation of a geometric Brownian motion model requires the use of highly subjective assumptions to estimate the fair value of stock-based awards. These assumptions include the following estimates.

•

Volatility: The Company calculates the estimated volatility rate based on the volatilities of common stock of comparable companies in its industry.

•

Contractual term: The expected life of the warrants, which is based on the contractual term of the warrants.

•

Expected dividend yield: The Company has never declared or paid any cash dividends and does not currently plan to pay cash dividends in the foreseeable future. Consequently, the Company used an expected dividend yield of zero.

•

Risk-free rate: The risk-free interest rate is based on the U.S. Treasury rate for similar periods as those of expected volatility.

Commitments and Contingencies

9 Months Ended

Sep. 30, 2019

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

Note 6. Commitments and Contingencies

Facility Leases

The Company’s previous operating lease for its headquarters facility office space in Redwood City, California, terminated in August 2019. In July 2019, the Company executed a non-cancellable lease agreement for 6,368 square feet of new space in Redwood City, California, which began in September 2019 and expires in May 2021. The lease also provides the Company with the right to use office furniture in the space and allows the purchase of this furniture at the end of the lease term for $1. The lease agreement requires monthly lease payments of approximately $29,000 beginning in November of 2019, with an increase to approximately $30,000 per month in September of 2020. The Company has accounted for the new lease as an operating lease for the office space and a capital lease for the office furniture, based on their relative fair values. The gross value of office furniture under this capital lease was approximately $27,000.

Rent expense was approximately $65,000 and $78,000 during the three months ended September 30, 2019 and 2018, respectively, net of sublease income of approximately $43,000 and $39,000, respectively. Rent expense was approximately $167,000 and $246,000 during the nine months ended September 30, 2019 and 2018, respectively, net of sublease income of approximately $173,000 and $237,000, respectively.

The following is a schedule by year of future minimum lease payments under the Company’s lease agreement as of September 30, 2019 (in thousands):

	Capital Lease			Operating Lease		Total
Remaining of 2019	$	3		$	56	$	59
2020		19			336		355
2021		8			143		151
Total		30		$	535	$	565
Less: Amount representing interest		(2	)
Present value of minimum lease payments	$	28

Contingencies

In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for general indemnifications. The Company’s exposure under these agreements is unknown because it involves claims that may be made against the Company in the future but have not yet been made. The Company accrues a liability for such matters when it is probable that future expenditures will be made, and such expenditures can be reasonably estimated.

CoSense Joint Venture Agreement and Discontinued Operations

9 Months Ended

Sep. 30, 2019

Discontinued Operations And Disposal Groups [Abstract]

CoSense Joint Venture Agreement and Discontinued Operations

Note 7. CoSense Joint Venture Agreement and Discontinued Operations

In December 2017, the Company entered into a joint venture with OptAsia Healthcare Limited, or OAHL, with respect to its CoSense product by agreeing to sell shares of Capnia, its then wholly-owned subsidiary, to OAHL. CoSense was Soleno’s first Sensalyze Technology Platform product to receive 510(k) clearances from the FDA and CE Mark certification. CoSense measures CO, which can be elevated due to endogenous causes such as excessive breakdown of red blood cells, or hemolysis, or exogenous causes such as CO poisoning and smoke inhalation. The first target market for CoSense is for the use of ETCO measurements to aid in detection of hemolysis in neonates, a disorder in which CO and bilirubin are produced in excess as byproducts of the breakdown of red blood cells. The Company’s entry into the joint venture resulted from a comprehensive review of strategic alternatives for its legacy products and product candidates following its transition to a primarily therapeutic drug product company. The terms of the Joint Venture Agreement provide that OAHL would invest up to a total of $2.2 million in Capnia’s common shares on an incremental quarterly basis commencing in December 2017. OAHL was also responsible for funding a portion of the Capnia operations. The Joint Venture Agreement provided that Capnia would issue shares of common stock to OAHL based on a negotiated price of $1.00 per share when the cumulative investment made by OAHL equaled or exceeded $1.2 million. For financial reporting purposes, Capnia’s assets, liabilities and results of operations had historically been consolidated with those of the Company.

During October 2018, the Company and OAHL determined and agreed that the cumulative investment made by OAHL exceeded $1.2 million during the quarter ended September 30, 2018. Accordingly, on October 16, 2018, Capnia issued 1,690,322 shares of its common stock to OAHL, representing 53% of its outstanding shares. After the share issuance the Company no longer held a controlling interest in Capnia and resulted in the deconsolidation of Capnia’s financial statements from those of the Company and a $2.0 million gain was recognized in the fourth quarter of 2018 as a result of the deconsolidation. Of this amount, $1.2 million related to the remeasurement of the Company's retained interest in the joint venture to fair value which was measured based on the negotiated price of $1.00 per share for Soleno’s remaining ownership of 1,480,000 shares less a 23% discount for lack of control over Capnia. The total gain was included in other income from continuing operations on the Company's consolidated statements of operations. The remaining 47% investment in Capnia was classified as an equity method investment and presented as a Minority interest investment in former subsidiary in the condensed consolidated balance sheet. The balance of Minority interest investment in former subsidiary decreased by approximately $156,000 and $511,000 during the three and nine months ended September 30, 2019, respectively, as a result of the Company recording its share of Capnia’s net losses during the period, which is included in the line titled “Loss from minority interest investment” in the Company’s condensed consolidated statements of operations. During September 2019, the Company sold its remaining 47% investment in Capnia to Sinon Investments LLC (“Sinon”) for a total purchase price of $500,000. As of the sale date, the Company had a minority interest investment in former subsidiary balance of approximately $467,000, after recording approximately $511,000 for its share of Capnia’s losses during 2019 up until the date of sale. A gain of approximately $33,000 was recognized upon the sale and is presented, together with the Company’s share of Capnia’s net losses during the period, in the condensed consolidated statements of operations in the line titled “Loss from minority interest investment”. Following the transaction, the Company has no interest remaining in Capnia and the previous joint venture agreement with OAHL has been terminated.

There were no assets or liabilities held for sale as of September 30, 2019, or December 31, 2018, after the deconsolidation of Capnia in October 2018, and no discontinued operations during the three and nine months ended September 30, 2019. The components of the Statements of Operations presented as Discontinued Operations during the three and nine months ended September 30, 2018 follow (in thousands).



	Three Months Ended September 30, 2018			Nine Months Ended September 30, 2018

Product revenue	$	6		$	60
Cost of product revenue		2			30
Gross profit (loss)		4			30
Expenses
Research and development		306			1,009
Sales and marketing		1			25
General and administrative		124			360
Total expenses		431			1,394
Net loss from discontinued operations	$	(427	)	$	(1,364	)

Stock-based compensation expense of approximately $20,000 and $58,000 was classified in discontinued operations for the three and nine months ended September 30, 2018, respectively. There were no discontinued operations during the three and nine months ended September 30, 2019.

Stockholders' Equity

9 Months Ended

Sep. 30, 2019

Equity [Abstract]

Stockholders' Equity

Note 8. Stockholders’ Equity

Equity Incentive Plans

The Company has adopted the 1999 Incentive Stock Plan, the 2010 Equity Incentive Plan, and the 2014 Equity Incentive Plan, or the 2014 Plan, and together, the Plans. The 1999 Incentive Stock Plan expired in 2009, and the 2010 Equity Incentive Plan has been closed to new issuances. Under the 2014 Plan the Company may grant stock options, stock appreciation rights, restricted stock, restricted stock units, performance units or performance shares to employees, directors, advisors, and consultants. Options granted under the 2014 Plan may be incentive stock options (“ISOs”) or nonqualified stock options (“NSOs”). ISOs may be granted only to Company employees, including officers and directors.

The Board of Directors has the authority to determine to whom stock options will be granted, the number of options, the term, and the exercise price. Options are to be granted at an exercise price not less than fair value. For individuals holding more than 10% of the voting rights of all classes of stock, the exercise price of an option will not be less than 110% of fair value. The vesting period is normally monthly over a period of 4 years from the vesting date. The contractual term of an option is no longer than five years for ISOs for which the grantee owns greater than 10% of the voting power of all classes of stock and no longer than ten years for all other options. The terms and conditions governing restricted stock units is at the sole discretion of the Board. As of September 30, 2019, a total of 905,532 shares are available for future grant under the 2014 Plan.

The Company recognized stock-based compensation expense related to options and restricted stock units granted to employees, directors and consultants for the three and nine months ended September 30, 2019 of approximately $153,000 and $530,000, respectively. Stock-based compensation expense related to options and restricted stock units granted to employees, directors and consultants during the three and nine months ended September 30, 2018 was approximately $231,000 and $789,000, respectively, of which approximately $20,000 and $58,000, was recorded in discontinued operations in the three and nine months ended September 30, 2018, respectively. There were no discontinued operations during the nine months ended September 30, 2019. The compensation expense is allocated on a departmental basis, based on the classification of the option holder. No income tax benefits have been recognized in the statements of operations for stock-based compensation arrangements during any of the periods presented.

Stock compensation expense was allocated between departments in continuing operations as follows (in thousands).

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Research and development	$	42	$	34	$	124	$	174
General and administrative		111		177		406		557
Total	$	153	$	211	$	530	$	731

Stock Options

The Company granted options to purchase 565,785 and 736,086 of the Company’s common stock during the nine months ended September 30, 2019 and 2018, respectively. There were no options granted during the three months ended September 30, 2019 or 2018. The fair value of each award granted was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions.

	Nine Months Ended September 30,
	2019	2018
Expected life (years)	5.5-6.1	5.5-6.02
Risk-free interest rate	1.9%-2.6%	2.7%-2.8%
Volatility	70%-71%	70%
Dividend rate	— %	— %

The Black-Scholes option-pricing model requires the use of highly subjective assumptions to estimate the fair value of stock-based awards. These assumptions include the following estimates:

•

Expected life: The expected life of stock options represents the average of the contractual term of the options and the weighted-average vesting period, as permitted under the simplified method. The Company does not believe it is able to rely on historical exercise and post-vesting termination activity to provide accurate data for estimating the expected term for use in estimating the fair value-based measurement of stock options. Therefore, it has opted to use the “simplified method” for estimating the expected term of options.

•

Risk-free interest rate: The risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected time to liquidity.

•

Volatility: The estimated volatility rate based on the volatilities of common stock of comparable companies in the Company’s industry.

•

Dividend rate: The Company has never declared or paid any cash dividends and does not presently plan to pay cash dividends in the foreseeable future. Consequently, the Company used an expected dividend yield of zero.

The following table summarizes stock option transactions for the nine months ended September 30, 2019 as issued under the Plans:

	Shares Available			Number of Options			Weighted- Average Exercise Price per		Weighted Average Remaining Contractual Term
	for Grant			Outstanding			Share		(in years)
Balance at December 31, 2018		1,150,961			1,667,153		$	6.03		8.27
Additional shares authorized		223,742
Options granted		(565,785	)		565,785		$	1.82
Options exercised		—			—			—
Options canceled/forfeited		96,614			(96,614	)	$	4.75
Balance at September 30, 2019		905,532			2,136,324		$	4.97		8.02
Options vested at September 30, 2019					1,104,712		$	7.79		7.34
Options vested and expected to vest at September 30, 2019					2,136,324		$	4.97		8.02

The weighted-average grant date fair value of options granted was $1.17 and $1.09 per share for the nine months ended September 30, 2019 and 2018, respectively. At September 30, 2019 total unrecognized employee stock-based compensation was $1.2 million, which is expected to be recognized over the weighted-average remaining vesting period of 2.5 years. As of September 30, 2019, the outstanding stock options had an intrinsic value of zero.

Restricted Stock Units

There were 99,217 restricted stock units granted by the Company during the nine months ended September 30, 2018 to employees and nonemployees. The shares were 100% vested on the grant date and were valued based on the Company’s common stock price on the grant date, with approximately $159,000 of the related stock-based compensation expense recognized at that time. There were no restricted stock units granted by the Company during the nine months ended September 30, 2019.

2014 Employee Stock Purchase Plan

The Company’s board of directors and stockholders have adopted the 2014 Employee Stock Purchase Plan, or the ESPP. The ESPP has become effective, and the board of directors will implement commencement of offers thereunder in its discretion. A total of 27,967 shares of the Company’s common stock has been made available for sale under the ESPP. In addition, the ESPP provides for annual increases in the number of shares available for issuance under the plan on the first day of each year beginning in the year following the initial date that the board of directors authorizes commencement, equal to the least of:

•

1.0% of the outstanding shares of the Company’s common stock on the first day of such year;

•

55,936 shares; or

•

such amount as determined by the board of directors.

As of September 30, 2019, there were no purchases by employees under this plan.

Series D Warrants

The Company issued 256,064 Series D Warrants in October 2015, which are exercisable into 586,182 shares of the Company’s common stock, with an exercise price of $12.30 and a term of five years expiring on October 15, 2020. The Company’s Series D Warrants contain standard anti-dilution provisions for stock dividends, stock splits, subdivisions, combinations and similar types of recapitalization events. They also contain a cashless exercise feature that provides for their net share settlement at the option of the holder in the event that there is no effective registration statement covering the continuous offer and sale of the warrants and underlying shares. The Company is required to comply with certain requirements to cause or maintain the effectiveness of a registration statement for the offer and sale of these securities. The Series D Warrant agreement further provides for the payment of liquidated damages at an amount per month equal to 1% of the aggregate VWAP of the shares into which each Series D Warrant is convertible in the event that the Company is unable to maintain the effectiveness of a registration statement as described herein. The Company evaluated the registration payment arrangement stipulated in the terms of this securities agreement and determined that it is probable that the Company will maintain an effective registration statement and has therefore not allocated any portion of the proceeds to the registration payment arrangement. The Series D Warrant agreement specifically provides that under no circumstances will the Company be required to settle any Series D Warrant exercise for cash, whether by net settlement or otherwise.

Accounting Treatment

The Company accounts for the Series D Warrants in accordance with the guidance in ASC 815 Derivatives and Hedging. As indicated above, the Company is not required under any circumstance to settle any Series D Warrant exercise for cash. The Company has therefore classified the value of the Series D Warrants as permanent equity.

Other Common Stock Warrants

As of September 30, 2019, the Company had 102,070 common stock warrants outstanding from the 2010/2012 convertible notes, with an exercise price of $24.35 and a term of 10 years expiring in November 2024. The Company also had 16,500 common stock warrants issued to the underwriter in the Company’s IPO, with an exercise price of $35.70 and a term of 10 years, expiring in November 2024.

Net income (loss) per share

9 Months Ended

Sep. 30, 2019

Earnings Per Share [Abstract]

Net loss per share

Note 9. Net income (loss) per share

Basic net loss per share is computed by dividing net loss by the weighted-average number of common stock actually outstanding during the period. Diluted net loss per share is computed by dividing net loss by the weighted-average number of common stock outstanding and dilutive potential common stock that would be issued upon the exercise of common stock options and warrants.

The following table presents the calculation of basic and diluted earnings per share (in thousands, except per-share amounts):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Numerator:
Income (loss) from continuing operations	$	889		$	(2,309	)	$	(16,149	)	$	(12,234	)
Loss from discontinued operations		—			(427	)		—			(1,364	)
Net income (loss) - basic		889			(2,736	)		(16,149	)		(13,598	)
Less: noncash income from change in fair value of warrants		7,090			—			906			—
Net loss - diluted	$	(6,201	)	$	(2,736	)	$	(17,055	)	$	(13,598	)

Denominator:
Basic weighted-average common shares outstanding		31,793,292			21,432,482			31,775,590			20,443,044

Effect of dilutive securities:
Options to purchase common stock		260,882			—			236,395			—
Warrants		389,473			—			223,543			—
Diluted weighted-average common shares outstanding		32,443,647			21,432,482			32,235,528			20,443,044

Income (loss) per common share from continuing operations:
Basic	$	0.03		$	(0.11	)	$	(0.51	)	$	(0.60	)
Diluted	$	(0.19	)	$	(0.11	)	$	(0.53	)	$	(0.60	)
Loss per common share from discontinued operations:
Basic	$	-		$	(0.02	)	$	-		$	(0.07	)
Diluted	$	-		$	(0.02	)	$	-		$	(0.07	)
Net income (loss) per common share:
Basic	$	0.03		$	(0.13	)	$	(0.51	)	$	(0.67	)
Diluted	$	(0.19	)	$	(0.13	)	$	(0.53	)	$	(0.67	)

The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted-average shares outstanding for the periods presented because such securities have an antidilutive impact, either due to the losses reported or because the exercise price was greater than the average market price of the common shares during the period.

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Warrants issued to 2010/2012 convertible note holders to purchase common stock		102,070		102,070		102,070		102,070
Options to purchase common stock		1,875,442		1,667,896		1,899,930		1,667,896
Warrants issued in 2009 to purchase common stock		—		1,851		—		1,851
Warrants issued to underwriter to purchase common stock		16,500		16,500		16,500		16,500
Series A warrants to purchase common stock		485,121		485,121		485,121		485,121
Series C warrants to purchase common stock		118,083		118,083		118,083		118,083
Series D warrants to purchase common stock		586,162		586,182		586,162		586,182
2017 PIPE warrants		5,665,548		6,024,425		5,818,443		6,024,425
2018 PIPE warrants		483,021		—		496,056		—
Total		9,331,947		9,002,128		9,522,365		9,002,128

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP, and the applicable rules and regulations of the SEC for interim financial information. Accordingly, they do not include all of the information and notes required by GAAP for complete financial statements. The condensed consolidated balance sheet at December 31, 2018, has been derived from the audited consolidated financial statements at that date, but does not include all disclosures, including notes, required by GAAP for complete financial statements. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and, in the opinion of management, reflect all adjustments of a normal recurring nature that are necessary for a fair presentation of the results for the interim periods presented. The interim results are not necessarily indicative of the results for any future interim period or for the entire year. The accompanying condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto for the year ended December 31, 2018, included in the Company’s Annual Report on Form 10-K.
Recent Accounting Standards	Recent Accounting Standards Recently Adopted Accounting Standards In June 2018, the FASB issued ASU 2018-07, “Compensation – Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting”, to simplify the accounting for share-based payments to nonemployees by aligning it with the accounting for share-based payments to employees, with certain exceptions. Under the guidance, the measurement of equity-classified nonemployee awards is fixed at the grant date, which may lower the cost and reduce volatility in the income statement. This ASU was early adopted by the Company at the beginning of 2019. Its adoption did not have a material impact on the Company’s condensed consolidated financial statements. In August 2018, SEC adopted the final rule under SEC Release No. 33-10532, “Disclosure Update and Simplification”, amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of stockholders’ equity for interim financial statements. Under the amendments, an analysis of changes in each caption of stockholders’ equity presented in the balance sheet must now be provided in a note or separate statement. The Company has applied this new guidance to its condensed financial statements beginning in the first quarter of 2019. Recently Issued Accounting Standards In February 2016, the FASB issued ASU 2016-02: “Leases (Topic 842)”. ASU 2016-02 provides new comprehensive lease accounting guidance that supersedes existing lease guidance. Upon adoption of ASU 2016-02, the Company may elect to apply the transition approach either as of the beginning of the earliest period presented in the financial statements – in which case it would restate its comparative periods, or as of the beginning of the period of adoption – in which case it would not restate its comparative periods. ASU 2016-02 requires the Company to capitalize most current operating lease obligations as right-of-use assets with a corresponding liability based on the present value of future operating lease obligations. Criteria for distinguishing leases between finance and operating are substantially similar to criteria for distinguishing between capital leases and operating leases in existing lease guidance. Lease agreements that are 12 months or less are permitted to be excluded from the balance sheet. Topic 842 includes a number of optional practical expedients that the Company may elect to apply. Expanded disclosures with additional qualitative and quantitative information will also be required. The adoption will include updates as provided under ASU 2018-01, Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842, ASU 2018-10, Codification Improvements to Topic 842, Leases, ASU 2018-20, Leases (Topic 842): Narrow-Scope Improvements for Lessors and ASU 2019-01, Leases (Topic 842): Codification Improvements. Topic 842 is effective for public entities with fiscal years beginning after December 15, 2018 and for all other entities for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2020. As the Company is an emerging growth company and elected to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act, Topic 842 will be effective for the Company beginning in fiscal 2020, although early adoption is permitted. The Company will adopt the new lease standard effective beginning in the fiscal year beginning January 1, 2020 using a modified retrospective method and will not restate comparative periods. The Company currently believes that its operating lease commitments will be subject to the new standard and recognized as an operating lease liability and right-of-use asset upon the adoption of Topic 842, which will increase the Company’s total assets and total liabilities in its condensed consolidated balance sheet. In July 2017, the FASB issued ASU 2017-11, “Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815): (Part I) Accounting for Certain Financial Instruments with Down Round Features; (Part II) Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception”, (ASU 2017-11). Part I of this update addresses the complexity of accounting for certain financial instruments with down round features. Down round features are features of certain equity-linked instruments (or embedded features) that result in the strike price being reduced on the basis of the pricing of future equity offerings. Current accounting guidance creates cost and complexity for entities that issue financial instruments (such as warrants and convertible instruments) with down round features that require fair value measurement of the entire instrument or conversion option. Part II of this update addresses the difficulty of navigating Topic 480, Distinguishing Liabilities from Equity, because of the existence of extensive pending content in the FASB Accounting Standards Codification. This pending content is the result of the indefinite deferral of accounting requirements about mandatorily redeemable financial instruments of certain nonpublic entities and certain mandatorily redeemable noncontrolling interests. The amendments in Part II of this update do not have an accounting effect. The amendments in Part I of ASU 2017-11 are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. For all other entities, the amendments in Part I are effective for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2020. As the Company is an emerging growth company and elected to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act, this ASU 2017-11 will be effective for the Company beginning in fiscal 2020, although early adoption is permitted. The Company is currently assessing the potential impact of adopting ASU 2017-11 on its condensed consolidated financial statements and related disclosures. In August 2018, the FASB issued ASU 2018-13, “Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement”. The ASU modifies the disclosure requirements for fair value measurements by removing, modifying, or adding certain disclosures. This ASU is effective for the Company beginning in 2020. Early adoption is permitted. An entity is permitted to early adopt any removed or modified disclosures upon issuance of ASU No. 2018-13 and delay adoption of the additional disclosures until their effective date. The Company has not yet evaluated the impact of adoption of this ASU on its condensed consolidated financial statements disclosures.

Fair Value of Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Summary of Financial Instruments Measured at Fair Value on Recurring Basis

The following table sets forth the Company’s financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands).

	Fair Value Measurements at September 30, 2019
	Total		Level 1		Level 2		Level 3
Liabilities
Series A warrant liability	$	25	$	25	$	—	$	—
2017 PIPE warrant liability		3,667		—		—		3,667
2018 PIPE warrant liability		590		—		—		590
Essentialis purchase price contingency liability		6,066		—		—		6,066
Total common stock warrant and contingent consideration liability	$	10,348	$	25	$	—	$	10,323

	Fair Value Measurements at December 31, 2018
	Total		Level 1		Level 2		Level 3
Liabilities
Series A warrant liability	$	49	$	49	$	—	$	—
2017 PIPE warrant liability		4,563		—		—		4,563
2018 PIPE warrant liability		600		—		—		600
Essentialis purchase price contingency liability		5,649		—		—		5,649
Total common stock warrant and contingent consideration liability	$	10,861	$	49	$	—	$	10,812

Summary of Changes in Fair Value of Level1 and Level 3 Financial Instruments

The following table sets forth a summary of the changes in the fair value of the Company’s Level 1 and Level 3 warrants, which are treated as liabilities (dollars in thousands).

	Series A Warrant					Series C Warrant				2017 PIPE Warrants					2018 PIPE Warrants					Purchase Price
	Number of Warrants		Liability			Number of Warrants		Liability		Number of Warrants		Liability			Number of Warrants		Liability			Contingent Liability
Balance at December 31, 2018		485,121	$	49			118,083	$	—		6,024,425	$	4,563			513,617	$	600		$	5,649
Change in value of Series A Warrants		—		(24	)		—		—		—		—			—		—			—
Change in value of 2017 PIPE Warrants		—		—			—		—		—		(896	)		—		—			—
Change in value of 2018 PIPE Warrants		—		—			—		—		—		—			—		(10	)		—
Change in value of contingent liability		—		—			—		—		—		—			—		—			417
Balance at September 30, 2019		485,121	$	25			118,083	$	—		6,024,425	$	3,667			513,617	$	590		$	6,066

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

Warrant Liabilities (Tables)

9 Months Ended

Sep. 30, 2019

Series C Warrant [Member]

Fair Value of Convertible Preferred Stock Warrant Liability

The Company used the following inputs.

	September 30, 2019			December 31, 2018
Volatility		90	%		90	%
Contractual term (years)		0.42			1.17
Expected dividend yield		—	%		—	%
Risk-free rate		1.85	%		2.60	%

2017 PIPE Warrant Liability [Member]

Fair Value of Convertible Preferred Stock Warrant Liability

The following summarizes certain key assumptions used in estimating the fair values.

	September 30, 2019			December 31, 2018
Volatility		85	%		75	%
Contractual term (years)		1.2			2.0
Expected dividend yield		—	%		—	%
Risk-free rate		1.80	%		2.51	%

2018 PIPE Warrant Liability [Member]

Fair Value of Convertible Preferred Stock Warrant Liability

The following summarizes certain key assumptions used in estimating the fair values.

	September 30, 2019			December 31, 2018
Volatility		85	%		75	%
Contractual term (years)		4.2			5.0
Expected dividend yield		—	%		—	%
Risk-free rate		1.56	%		2.51	%

CoSense Joint Venture Agreement and Discontinued Operations (Tables)

9 Months Ended

Sep. 30, 2019

Discontinued Operations And Disposal Groups [Abstract]

Components of Discontinued Operations



	Three Months Ended September 30, 2018			Nine Months Ended September 30, 2018

Product revenue	$	6		$	60
Cost of product revenue		2			30
Gross profit (loss)		4			30
Expenses
Research and development		306			1,009
Sales and marketing		1			25
General and administrative		124			360
Total expenses		431			1,394
Net loss from discontinued operations	$	(427	)	$	(1,364	)

- Definition

Tabular disclosure of information related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5D
-URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721677-107760

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 45
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-URI http://asc.fasb.org/extlink&oid=109222160&loc=SL51721533-107759

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 205
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-URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721659-107760

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721665-107760

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
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-URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2941-110230

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
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-URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721675-107760

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 205
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721683-107760

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
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Reference 11: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721671-107760

Reference 12: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 205
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Reference 13: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721663-107760

+ Details

Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2019

Equity [Abstract]

Summary of Stock Based Compensation Expense

Stock compensation expense was allocated between departments in continuing operations as follows (in thousands).

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Research and development	$	42	$	34	$	124	$	174
General and administrative		111		177		406		557
Total	$	153	$	211	$	530	$	731

Schedule of Fair Value of Award Granted Using Black-Scholes Option Pricing Model

The fair value of each award granted was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions

	Nine Months Ended September 30,
	2019	2018
Expected life (years)	5.5-6.1	5.5-6.02
Risk-free interest rate	1.9%-2.6%	2.7%-2.8%
Volatility	70%-71%	70%
Dividend rate	— %	— %

Summary of Stock Option Transactions

The following table summarizes stock option transactions for the nine months ended September 30, 2019 as issued under the Plans:

	Shares Available			Number of Options			Weighted- Average Exercise Price per		Weighted Average Remaining Contractual Term
	for Grant			Outstanding			Share		(in years)
Balance at December 31, 2018		1,150,961			1,667,153		$	6.03		8.27
Additional shares authorized		223,742
Options granted		(565,785	)		565,785		$	1.82
Options exercised		—			—			—
Options canceled/forfeited		96,614			(96,614	)	$	4.75
Balance at September 30, 2019		905,532			2,136,324		$	4.97		8.02
Options vested at September 30, 2019					1,104,712		$	7.79		7.34
Options vested and expected to vest at September 30, 2019					2,136,324		$	4.97		8.02

Net income (loss) per share (Tables)

9 Months Ended

Sep. 30, 2019

Earnings Per Share [Abstract]

Schedule of Calculations of Basic and Diluted Earnings Per Share

The following table presents the calculation of basic and diluted earnings per share (in thousands, except per-share amounts):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Numerator:
Income (loss) from continuing operations	$	889		$	(2,309	)	$	(16,149	)	$	(12,234	)
Loss from discontinued operations		—			(427	)		—			(1,364	)
Net income (loss) - basic		889			(2,736	)		(16,149	)		(13,598	)
Less: noncash income from change in fair value of warrants		7,090			—			906			—
Net loss - diluted	$	(6,201	)	$	(2,736	)	$	(17,055	)	$	(13,598	)

Denominator:
Basic weighted-average common shares outstanding		31,793,292			21,432,482			31,775,590			20,443,044

Effect of dilutive securities:
Options to purchase common stock		260,882			—			236,395			—
Warrants		389,473			—			223,543			—
Diluted weighted-average common shares outstanding		32,443,647			21,432,482			32,235,528			20,443,044

Income (loss) per common share from continuing operations:
Basic	$	0.03		$	(0.11	)	$	(0.51	)	$	(0.60	)
Diluted	$	(0.19	)	$	(0.11	)	$	(0.53	)	$	(0.60	)
Loss per common share from discontinued operations:
Basic	$	-		$	(0.02	)	$	-		$	(0.07	)
Diluted	$	-		$	(0.02	)	$	-		$	(0.07	)
Net income (loss) per common share:
Basic	$	0.03		$	(0.13	)	$	(0.51	)	$	(0.67	)
Diluted	$	(0.19	)	$	(0.13	)	$	(0.53	)	$	(0.67	)

Schedule of Potentially Dilutive Securities Outstanding Excluded from Computations of Diluted Weighted-Average Shares Outstanding

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Warrants issued to 2010/2012 convertible note holders to purchase common stock		102,070		102,070		102,070		102,070
Options to purchase common stock		1,875,442		1,667,896		1,899,930		1,667,896
Warrants issued in 2009 to purchase common stock		—		1,851		—		1,851
Warrants issued to underwriter to purchase common stock		16,500		16,500		16,500		16,500
Series A warrants to purchase common stock		485,121		485,121		485,121		485,121
Series C warrants to purchase common stock		118,083		118,083		118,083		118,083
Series D warrants to purchase common stock		586,162		586,182		586,162		586,182
2017 PIPE warrants		5,665,548		6,024,425		5,818,443		6,024,425
2018 PIPE warrants		483,021		—		496,056		—
Total		9,331,947		9,002,128		9,522,365		9,002,128

Going Concern and Management's Plans - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended						9 Months Ended
	Oct. 25, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Liquidity And Managements Plans [Line Items]
Net loss		$ 889	$ (10,008)	$ (7,030)	$ (2,736)	$ (7,058)	$ (3,804)	$ (16,149)	$ (13,598)
Accumulated deficit		(143,181)						(143,181)		$ (127,032)
Positive (deficit) in working capital		$ 8,200						8,200
Net cash used in operating activities								$ (12,299)	$ (7,947)
Underwritten Public Offering [Member] \| Subsequent Event [Member]
Liquidity And Managements Plans [Line Items]
Number of newly issued	12,841,667
Price per unit	$ 1.20
Net proceeds from shares issued	$ 14,500

Warrant Liabilities - Additional Information (Detail)			1 Months Ended	3 Months Ended		9 Months Ended
Warrant Liabilities - Additional Information (Detail)	Apr. 30, 2015 $ / shares	Mar. 05, 2015 USD ($) $ / shares shares	Jul. 31, 2015 USD ($) shares	Sep. 30, 2019 USD ($) $ / shares shares	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) $ / shares shares	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 19, 2018 $ / shares shares	Dec. 15, 2017 $ / shares shares
Class Of Warrant Or Right [Line Items]
Change in fair value of stock warrants				$ (7,116,000)	$ (1,543,000)	$ (930,000)	$ 1,549,000
Expected Dividend Yield [Member]
Class Of Warrant Or Right [Line Items]
Measurement input				0.00		0.00
Series A Warrants to Purchase Shares of Common Stock [Member] \| IPO [Member]
Class Of Warrant Or Right [Line Items]
Number of common stock purchased upon issuance of warrants \| shares				489,921		489,921
Exercise price of warrants exercised \| $ / shares				$ 32.50		$ 32.50
Warrants term						5 years
Series A Warrant Liability [Member]
Class Of Warrant Or Right [Line Items]
Aggregate VWAP (percent)						1.00%
Warrants exercised (in shares) \| shares						4,800
Warrants outstanding (in shares) \| shares				485,121		485,121
Warrant liability				$ 25,000		$ 25,000		$ 49,000
Change in fair value of stock warrants				$ (26,000)		$ (24,000)
Series B Warrant Liability [Member]
Class Of Warrant Or Right [Line Items]
Exercise price of warrants exercised \| $ / shares		$ 32.50
Warrants exercised (in shares) \| shares		117,902
De-recognition of warrant liability		$ 6,700,000
Proceeds from exercise of warrants		$ 3,800,000
Series C Warrant [Member]
Class Of Warrant Or Right [Line Items]
Number of common stock purchased upon issuance of warrants \| shares				118,083		118,083
Exercise price of warrants exercised \| $ / shares	$ 31.25	$ 31.25
Aggregate VWAP (percent)						1.00%
Warrant liability				$ 0		$ 0
Tender offer expiration date	Mar. 05, 2020	Mar. 05, 2020
Proceeds from issuance of common stock under tender offer			$ 6,000
Warrants cashless exercised (in shares) \| shares			181
Series C Warrant [Member] \| Common Stock [Member]
Class Of Warrant Or Right [Line Items]
Issuance of shares upon cashless exercise warrants (in shares) \| shares			181
2017 PIPE Warrant Liability [Member]
Class Of Warrant Or Right [Line Items]
Number of common stock purchased upon issuance of warrants \| shares										1
Exercise price of warrants exercised \| $ / shares										$ 2.00
Warrant liability				3,667,000		3,667,000		4,563,000
Change in fair value of stock warrants				(6,500,000)	$ (1,400,000)	$ (896,000)	$ 1,600,000
Warrant issuance description						The 2017 PIPE Warrants were issued on December 15, 2017 in the 2017 PIPE Offering, pursuant to a Warrant Agreement with each of the investors in the 2017 PIPE Offering, and entitle the holder to purchase one share of the Company’s common stock at an exercise price equal to $2.00 per share, subject to adjustment as discussed below, at any time commencing upon issuance of the 2017 PIPE Warrants and terminating at the earlier of December 15, 2020 or 30 days following positive Phase III results for the DCCR tablet in PWS.
Fair value of estimated warrants				$ 3,700,000		$ 3,700,000
2017 PIPE Warrant Liability to Purchase Common Stock [Member] \| Minimum [Member]
Class Of Warrant Or Right [Line Items]
Exercise price of warrants exercised \| $ / shares				$ 1.72		$ 1.72
2018 PIPE Warrant Liability [Member]
Class Of Warrant Or Right [Line Items]
Number of common stock purchased upon issuance of warrants \| shares									10,272,375
Exercise price of warrants exercised \| $ / shares									$ 2.00
Warrant liability				$ 590,000		$ 590,000		$ 600,000
Change in fair value of stock warrants				(555,000)		$ (10,000)
Warrant issuance description						The 2018 PIPE Warrants were issued on December 19, 2018 in the 2018 PIPE Offering, pursuant to a Warrant Agreement with each of the investors in the 2018 PIPE Offering, and entitle the holders of each of the 10,272,375 units to purchase 0.05 shares of the Company’s common stock at an exercise price equal to $2.00 per share, subject to adjustment as discussed below, at any time commencing upon issuance of the 2018 PIPE Warrants and terminating on December 21, 2023.
Fair value of estimated warrants				$ 590,000		$ 590,000
Warrant to call common stock \| shares									0.05
2018 PIPE Warrant Liability [Member] \| Minimum [Member]
Class Of Warrant Or Right [Line Items]
Exercise price of warrants exercised \| $ / shares				$ 2.00		$ 2.00

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended			3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Nov. 30, 2019 USD ($)	Jul. 31, 2019 USD ($) ft²	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)
Commitments and Contingencies [Line Items]
Rent expense				$ 65,000	$ 78,000	$ 167,000	$ 246,000
Sublease income				$ 43,000	$ 39,000	$ 173,000	$ 237,000
Redwood City, California [Member]
Commitments and Contingencies [Line Items]
Operating lease, description						The Company’s previous operating lease for its headquarters facility office space in Redwood City, California, terminated in August 2019. In July 2019, the Company executed a non-cancellable lease agreement for 6,368 square feet of new space in Redwood City, California, which began in September 2019 and expires in May 2021.
Operating lease, expiration			2021-05			2019-08
Area of operating lease \| ft²			6,368
Operating lease beginning date			2019-09
Payment to acquire office furniture under operating lease			$ 1
Gross value of office furniture under capital lease			$ 27,000
Redwood City, California [Member] \| Forecast [Member]
Commitments and Contingencies [Line Items]
Future minimum commitment under non-cancelable operating lease	$ 30,000	$ 29,000

Commitments and Contingencies - Schedule of Future Minimum Lease Payments (Detail) $ in Thousands	Sep. 30, 2019 USD ($)
Capital Lease
Remaining of 2019	$ 3
2020	19
2021	8
Total	30
Less: Amount representing interest	(2)
Present value of minimum lease payments	28
Operating Lease
Remaining of 2019	56
2020	336
2021	143
Total	535
Remaining of 2019	59
2020	355
2021	151
Total	$ 565

CoSense Joint Venture Agreement and Discontinued Operations - Additional Information (Detail)		3 Months Ended			9 Months Ended
	Oct. 16, 2018 shares	Sep. 30, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) $ / shares shares	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($) $ / shares
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Current period gain recognized			$ 2,000,000
Minority interest investment in former subsidiary			978,000
Loss from minority interest investment		$ (123,000)			$ (478,000)
Gain in minority interest investment					33,000,000
Loss from discontinued operations				$ (427,000)		$ (1,364,000)
Stock-based compensation expense		153,000		231,000	530,000	789,000
Discontinued Operations, Held-for-sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Stock-based compensation expense		0		20,000	0	58,000
CoSense, NFI and Serenz [Member] \| Discontinued Operations, Held-for-sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets held for sale, current		0	0		0
Assets held for sale, long-term		0	0		0
Liabilities held for sale, current		0	0		0
Liabilities held for sale, long-term		0	$ 0		0
Loss from discontinued operations		$ 0		$ (427,000)	0	$ (1,364,000)
Sinon Investments LLC [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total purchase price					$ 500,000,000
Capnia Inc Joint Venture [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Negotiated price per share \| $ / shares		$ 1.00			$ 1.00
Percentage of ownership interest					47.00%
Number of shares owned \| shares		1,480,000			1,480,000
Percentage of discount for lack of control					0.23
Decrease in minority interest investment		$ (156,000)			$ (511,000)
Loss from minority interest investment					$ (511,000,000)
Capnia Inc Joint Venture [Member] \| Sinon Investments LLC [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of ownership interest					47.00%
Minority interest investment in former subsidiary		467,000,000			$ 467,000,000
OAHL [Member] \| Capnia Inc Joint Venture [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Minority interest investment in former subsidiary		0			0
OAHL [Member] \| Capnia Inc Joint Venture [Member] \| Corporate Joint Venture [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Investment threshold requirement							$ 2,200,000
Negotiated price per share \| $ / shares							$ 1.00
Investment threshold requirement stock issuance		$ 1,200,000			$ 1,200,000		$ 1,200,000
Issuance of common stock (shares) \| shares	1,690,322
Percentage of ownership interest	53.00%

CoSense Joint Venture Agreement and Discontinued Operations - Components of Income of Discontinued Operations (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Expenses
Net loss from discontinued operations		$ (427,000)		$ (1,364,000)
CoSense, NFI and Serenz [Member] \| Discontinued Operations, Held-for-sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Product revenue		6,000		60,000
Cost of product revenue		2,000		30,000
Gross profit (loss)		4,000		30,000
Expenses
Research and development		306,000		1,009,000
Sales and marketing		1,000		25,000
General and administrative		124,000		360,000
Total expenses		431,000		1,394,000
Net loss from discontinued operations	$ 0	$ (427,000)	$ 0	$ (1,364,000)

Stockholders' Equity - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 31, 2015	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense		$ 153,000	$ 231,000	$ 530,000	$ 789,000
Expected dividend yield				0.00%	0.00%
Weighted average grant date fair value per option granted (in dollars per share)				$ 1.17	$ 1.09
Future stock-based compensation for unvested employee options granted and outstanding		1,200,000		$ 1,200,000
Stock options outstanding, intrinsic value		$ 0		$ 0
Number of shares available for issuance under the plan on the first day of each year		31,793,292		31,793,292		31,755,169
Series D Warrants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants outstanding (in shares)	256,064
Number of common stock purchased upon issuance of warrants	586,182
Exercise price of warrants (in dollars per share)	$ 12.30
Warrants term	5 years
Warrants expiration date	Oct. 15, 2020
Liquidated damages amount percent of VWAP (percent)	1.00%
Warrants to Purchase Stock [Member] \| 2010 and 2012 Convertible Promissory Notes [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants outstanding (in shares)		102,070		102,070
Exercise price of warrants (in dollars per share)		$ 24.35		$ 24.35
Warrants term				10 years
Warrants expiration period				2024-11
Underwriter [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants outstanding (in shares)		16,500		16,500
Exercise price of warrants (in dollars per share)		$ 35.70		$ 35.70
Warrants term				10 years
Warrants expiration period				2024-11
Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for grant		27,967		27,967
Percentage of outstanding stock maximum				1.00%
Number of shares available for issuance under the plan on the first day of each year		55,936		55,936
Discontinued Operations, Held-for-sale [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense		$ 0	20,000	$ 0	$ 58,000
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Ownership interest of voting rights of all classes of stock (percent)		10.00%		10.00%
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period				4 years
Number of shares available for grant		905,532		905,532		1,150,961
Income tax benefits recognized from stock-based compensation		$ 0	$ 0	$ 0	$ 0
Number of options granted		0	0	565,785	736,086
Future stock-based compensation, requisite service period				2 years 6 months
Stock Options [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair market value				110.00%
Stock Options [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Contractual term of option				10 years
ISOs [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Contractual term of option				5 years
Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense				$ 159,000
Stock units granted				0	99,217
Vesting percentage				100.00%

Stockholders' Equity - Summary of Stock Option Transactions (Detail) - Stock Options [Member] - $ / shares	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Shares Available for Grant
Options Available, Beginning balance			1,150,961
Options Available, Additional shares authorized			223,742
Options Available, Granted			(565,785)
Options Available, Exercised			0
Options Available, Canceled/Forfeited			96,614
Options Available, Ending balance	905,532		905,532		1,150,961
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance			1,667,153
Options granted	0	0	565,785	736,086
Options exercised			0
Options canceled/forfeited			(96,614)
Ending balance	2,136,324		2,136,324		1,667,153
Options vested at end of period (shares)			1,104,712
Options vested and expected to vest at end of period (shares)	2,136,324		2,136,324
Weighted-Average Exercise Price per Share
Beginning balance (in dollars per share)			$ 6.03
Options granted (in dollars per share)			1.82
Options exercised (in dollars per share)			0
Options canceled/forfeited (in dollars per share)			4.75
Ending balance (in dollars per share)	$ 4.97		4.97		$ 6.03
Options vested at end of period (in dollars per share)			7.79
Options vested and expected to vest at end of period (in dollars per share)	$ 4.97		$ 4.97
Weighted Average Remaining Contractual Term
Options outstanding at end of period			8 years 7 days		8 years 3 months 7 days
Options vested at end of period			7 years 4 months 2 days
Options vested and expected to vest at end of period			8 years 7 days

Net income (loss) per share - Schedule of Calculations of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator:
Income (loss) from continuing operations	$ 889	$ (2,309)	$ (16,149)	$ (12,234)
Loss from discontinued operations		(427)		(1,364)
Net income (loss) - basic	889	(2,736)	(16,149)	(13,598)
Less: noncash income from change in fair value of warrants	7,090		906
Net loss - diluted	$ (6,201)	$ (2,736)	$ (17,055)	$ (13,598)
Weighted-average common shares outstanding used in per-share calculation:
Basic weighted-average common shares outstanding	31,793,292	21,432,482	31,775,590	20,443,044
Effect of dilutive securities:
Options to purchase common stock	260,882		236,395
Warrants	389,473		223,543
Diluted weighted-average common shares outstanding	32,443,647	21,432,482	32,235,528	20,443,044
Income (loss) per common shares from continuing operations, basic	$ 0.03	$ (0.11)	$ (0.51)	$ (0.60)
Income (loss) per common shares from continuing operations, diluted	(0.19)	(0.11)	(0.53)	(0.60)
Loss per common share from discontinued operations, basic		(0.02)		(0.07)
Loss per common share from discontinued operations, diluted		(0.02)		(0.07)
Net income (loss) per common share, basic	0.03	(0.13)	(0.51)	(0.67)
Net income (loss) per common share, diluted	$ (0.19)	$ (0.13)	$ (0.53)	$ (0.67)

Fair Value of Financial Instruments - Summary of Changes in Fair Value of Level 1 and Level 3 Financial Instruments (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($) shares
Purchase price contingent liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period	$ 5,649
Change in value of liabilities	417
Balance at end of period	$ 6,066
Series A Warrant Liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the end of period, in shares \| shares	485,121
Series A Warrant Liability [Member] \| Common stock warrant liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period	$ 49
Balance at the beginning of period, in shares \| shares	485,121
Change in value of liabilities	$ (24)
Balance at end of period	$ 25
Balance at the end of period, in shares \| shares	485,121
Series C Warrant [Member] \| Common stock warrant liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period, in shares \| shares	118,083
Balance at the end of period, in shares \| shares	118,083
2017 PIPE Warrant Liability [Member] \| Common stock warrant liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period	$ 4,563
Balance at the beginning of period, in shares \| shares	6,024,425
Change in value of liabilities	$ (896)
Balance at end of period	$ 3,667
Balance at the end of period, in shares \| shares	6,024,425
2018 PIPE Warrant Liability [Member] \| Common stock warrant liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period	$ 600
Balance at the beginning of period, in shares \| shares	513,617
Change in value of liabilities	$ (10)
Balance at end of period	$ 590
Balance at the end of period, in shares \| shares	513,617

Warrant Liabilities - Fair Value of Convertible Preferred Stock Warrant Liability (Detail)	Sep. 30, 2019	Dec. 31, 2018
Expected Dividend Yield [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.00
Series C Warrant [Member] \| Volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.90	0.90
Series C Warrant [Member] \| Contractual Term [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement term	5 months 1 day	1 year 2 months 1 day
Series C Warrant [Member] \| Risk-free Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0185	0.0260
2017 PIPE Warrant Liability [Member] \| Volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.85	0.75
2017 PIPE Warrant Liability [Member] \| Contractual Term [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement term	1 year 2 months 12 days	2 years
2017 PIPE Warrant Liability [Member] \| Risk-free Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0180	0.0251
2018 PIPE Warrant Liability [Member] \| Volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.85	0.75
2018 PIPE Warrant Liability [Member] \| Contractual Term [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement term	4 years 2 months 12 days	5 years
2018 PIPE Warrant Liability [Member] \| Risk-free Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0156	0.0251

Stockholders' Equity - Summary of Stock Based Compensation Expense (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock compensation expense	$ 153,000	$ 231,000	$ 530,000	$ 789,000
Continuing Operations [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock compensation expense	153,000	211,000	530,000	731,000
Research and Development [Member] \| Continuing Operations [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock compensation expense	42,000	34,000	124,000	174,000
General and Administrative [Member] \| Continuing Operations [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock compensation expense	$ 111,000	$ 177,000	$ 406,000	$ 557,000

Fair Value of Contingent Consideration - Additional Information (Detail)			9 Months Ended	10 Months Ended
	Dec. 31, 2017 USD ($)	Mar. 07, 2017 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2017 USD ($)
Asset Acquisition [Line Items]
Fair value of stock consideration		$ 4,200,000
Fair value of cash consideration		1,100,000
Total purchase price consideration		5,300,000
First commercial sales milestone			$ 100,000,000
Second commercial sales milestone			200,000,000
Contingent liability payment on achievement of sales milestone		$ 2,600,000	$ 6,000,000
Changes Measurement [Member]
Asset Acquisition [Line Items]
Fair value of stock consideration	$ 2,700,000
Fair value of cash consideration	2,600,000
Total purchase price consideration	5,300,000
Essentialis, Inc. [Member]
Asset Acquisition [Line Items]
Value of deferred tax liability assumed	$ 1,700,000			$ 1,700,000
Increase (decrease) in valuation allowance				$ (1,700,000)
Essentialis, Inc. [Member] \| Measurement Input, Discount Rate [Member]
Asset Acquisition [Line Items]
Fair value inputs, discount rate (percent)		0.20
Essentialis, Inc. [Member] \| Earnout Payments [Member]
Asset Acquisition [Line Items]
Maximum potential cash earnout payments		$ 30,000,000

Subsequent Events - Additional Information (Detail) - Underwritten Public Offering [Member] - Subsequent Event [Member] $ / shares in Units, $ in Millions	Oct. 25, 2019 USD ($) $ / shares shares
Subsequent Event [Line Items]
Number of newly issued shares	12,841,667
Shares issued upon exercise of underwriters options	1,675,000
Shares issued price per share \| $ / shares	$ 1.20
Net proceeds from issuance of public offering \| $	$ 14.5

Fair Value of Financial Instruments - Summary of Financial Instruments Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Liabilities
Contingent liability for Essentialis purchase price	$ 6,066	$ 5,649
Series A Warrant Liability [Member]
Liabilities
Warrant liability	25	49
2017 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	3,667	4,563
2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	590	600
Fair Value, Measurements, Recurring [Member]
Liabilities
Total common stock warrant and contingent consideration liability	10,348	10,861
Fair Value, Measurements, Recurring [Member] \| Convertible preferred stock warrant liability [Member] \| Series A Warrant Liability [Member]
Liabilities
Warrant liability	25	49
Fair Value, Measurements, Recurring [Member] \| Convertible preferred stock warrant liability [Member] \| 2017 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	3,667	4,563
Fair Value, Measurements, Recurring [Member] \| Convertible preferred stock warrant liability [Member] \| 2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	590	600
Essentialis, Inc. [Member] \| Fair Value, Measurements, Recurring [Member]
Liabilities
Contingent liability for Essentialis purchase price	6,066	5,649
Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Liabilities
Total common stock warrant and contingent consideration liability	25	49
Level 1 [Member] \| Fair Value, Measurements, Recurring [Member] \| Convertible preferred stock warrant liability [Member] \| Series A Warrant Liability [Member]
Liabilities
Warrant liability	25	49
Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Liabilities
Total common stock warrant and contingent consideration liability	10,323	10,812
Level 3 [Member] \| Fair Value, Measurements, Recurring [Member] \| Convertible preferred stock warrant liability [Member] \| 2017 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	3,667	4,563
Level 3 [Member] \| Fair Value, Measurements, Recurring [Member] \| Convertible preferred stock warrant liability [Member] \| 2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	590	600
Level 3 [Member] \| Essentialis, Inc. [Member] \| Fair Value, Measurements, Recurring [Member]
Liabilities
Contingent liability for Essentialis purchase price	$ 6,066	$ 5,649