Collaborative Arrangements (Details) - USD ($)	1 Months Ended				3 Months Ended
	Sep. 30, 2015	Aug. 31, 2015	Jul. 31, 2014	Feb. 29, 2012	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2015
GlaxoSmithKline [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from license fees received			$ 6,000,000
Revenue recognized	$ 6,500,000						$ 5,000,000
Term of milestone agreement			3 years
Duration of technology transfer			3 years
Minimum milestone receivable			$ 5,750,000.00
Maximum milestone receivable			$ 38,500,000.0
License extension acceptance period			3 years
Termination notice period			90 days
License and services revenue					$ 500,000	$ 500,000
Deferred revenue					2,500,000			$ 3,000,000
Technology Transfer, Collaboration and License Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Termination notice period		30 days
Technology Transfer, Collaboration and License Agreement [Member] | Merck [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from license fees received		$ 5,000,000
Revenue recognized	$ 5,000,000
Contingent payment, completion of milestones and agreement		8,000,000
Potential royalty revenue		$ 15,000,000
Duration of license agreement		3 years
Right of refusal period		5 years
Termination notice period		90 days
License and services revenue					600,000
Deferred revenue					3,300,000			4,000,000
Upfront License fee, period for recognition		2 years
Contingent termination revenue		$ 8,000,000
Supply Agreement [Member] | Merck [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
License and services revenue					300,000	$ 500,000
Deferred revenue					$ 2,300,000			$ 1,000,000
Term of collaborative research and development agreement (years)				5 years
Optional extension period				5 years
Upfront License fee, period for recognition				5 years
Minimum [Member] | Technology Transfer, Collaboration and License Agreement [Member] | Merck [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Duration of technology transfer		15 months
Maximum [Member] | Technology Transfer, Collaboration and License Agreement [Member] | Merck [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Duration of technology transfer		24 months