Business (Details) - USD ($) $ in Thousands	3 Months Ended		51 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Net cash used for operating activities since January 2012	$ (13,003)	$ (5,509)	$ (57,900)
Cash and cash equivalents	$ 113,071	$ 42,712	$ 113,071	$ 126,467	$ 48,555