Organization and Basis of Presentation (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit	$ (325,342)	$ (268,096)
Cash and cash equivalents	117,185	37,900	$ 54,221	$ 39,734
Restricted cash	$ 600	$ 4,400