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 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 loss	(10,862)
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
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 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
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 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 loss	(17,038)
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
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 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