Background and Organization - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Background And Organization [Line Items]
Net loss from operations		$ (50,636)	$ (44,995)	$ (33,800)
Net cash used from operations		(28,156)	(39,849)	(27,469)
Cash and cash equivalents		$ 14,198	$ 20,667	$ 11,129	$ 26,529
Scenario, Forecast | 2017 Private Placement Common Stock Warrants
Background And Organization [Line Items]
Proceed from private placement and equity issuances, gross	$ 48,000