Liquidity, Financial Condition and Management's Plans - Additional Information (Detail) - USD ($) $ in Thousands			3 Months Ended
	Mar. 07, 2017	Jan. 27, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Liquidity And Managements Plans [Line Items]
Net loss			$ (2,887)	$ (3,189)
Accumulated deficit			101,199		$ 98,312
Positive (deficit) in working capital			9,600
Net cash used in operating activities			(2,183)	(3,984)
Shares issued for an investment (in shares)	8,333,333
Proceeds from issuance of common stock	$ 10,000		$ 10,000	$ 0
Aspire Capital Fund, LLC [Member]
Liquidity And Managements Plans [Line Items]
Maximum commitment under stock purchase agreement		$ 17,000
Agreement term		30 months
Shares issued during period (in shares)	2,083,333	708,333
Proceeds from issuance of common stock	$ 2,000	$ 2,000
Essentialis, Inc. [Member]
Liquidity And Managements Plans [Line Items]
Proceeds from issuance of common stock	$ 8,000