Condensed Consolidated Statements of Stockholders' Equity (Deficit) (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	S V B Leerink	Equity-classified awards	Common Shares	Common Shares S V B Leerink	Additional Paid-in Capital	Additional Paid-in Capital S V B Leerink	Additional Paid-in Capital Equity-classified awards	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning Balance at Dec. 31, 2018	$ (27,227)			$ 126		$ 567,655			$ 1	$ (595,009)
Beginning Balance (in shares) at Dec. 31, 2018				12,648
Issuance of common stock from the SVB Leerinksales agreement (net of issuance costs of $0.2million)		$ 7,512			$ 13		$ 7,499
Issuance of common stock from the SVB Leerink sales agreement (net of issuance costs of $0.2 million) (in shares)					1,252
Stock-based compensation expense related to equity- classified awards			$ 584					$ 584
Net income (loss)	555									555
Ending Balance at Mar. 31, 2019	(18,576)			$ 139		575,738			$ 1	(594,454)
Ending Balance (in shares) at Mar. 31, 2019				13,900
Beginning Balance at Dec. 31, 2019	14,846			$ 161		600,306				(585,621)
Beginning Balance (in shares) at Dec. 31, 2019				16,081
Stock-based compensation expense related to equity- classified awards			$ 543					$ 543
Net income (loss)	(8,381)									(8,381)
Ending Balance at Mar. 31, 2020	$ 7,008			$ 161		$ 600,849				$ (594,002)
Ending Balance (in shares) at Mar. 31, 2020				16,081