Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	2018 PIPE Warrant Liability [Member]	Series B Convertible Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member] 2018 PIPE Warrant Liability [Member]	Common Stock [Member] Essentialis, Inc. [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] 2018 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	829						829
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)			(4,571)	914,200
Issuance of restricted stock units under equity incentive plans	434						434
Issuance of restricted stock units under equity incentive plans (shares)				245,588
Issuance of common stock held back on acquisition of Essentialis						$ 1			$ (1)
Issuance of common stock held back on acquisition of Essentialis (Shares)						1,084,034
Issuance of common stock		$ 16,250			$ 11			$ 16,239
Issuance of common stock (shares)					10,272,375
Fair value at transaction date of warrants to purchase common stock		$ (582)						$ (582)
Net loss	(13,335)									(13,335)
Balances at ending at Dec. 31, 2018	30,413			$ 32			157,413			(127,032)
Balances at end (shares) at Dec. 31, 2018				31,755,169
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	693						693
Issuance of restricted stock units under equity incentive plans	132						132
Issuance of restricted stock units under equity incentive plans (shares)				61,218
Issuance of common stock	14,483			$ 13			14,470
Issuance of common stock (shares)				12,841,667
Net loss	(30,774)									(30,774)
Balances at ending at Dec. 31, 2019	$ 14,947			$ 45			$ 172,708			$ (157,806)
Balances at end (shares) at Dec. 31, 2019				44,658,054