Business Overview (Details) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
	May 06, 2016 USD ($) $ / shares shares	Sep. 30, 2016 USD ($) product	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) product	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of lead product candidates | product		2		2
Net cash (used in) operating activities				$ (91,987)	$ (70,675)
Cash and cash equivalents		$ 109,090	$ 41,916	109,090	41,916	$ 61,653	$ 146,470
Income (loss) from operations		(38,482)	$ (23,152)	(102,893)	(72,874)
Working Capital		$ 87,300		87,300
Subsidiary, Sale of Stock [Line Items]
Net proceeds from private placement				$ 89,845	$ 14,672
Private Placement
Subsidiary, Sale of Stock [Line Items]
Shares sold in private placement (in shares) | shares	29,948,334
Shares issued (in dollars per share) | $ / shares	$ 3.00
Net proceeds from private placement	$ 89,800