Collaborative Arrangements (Details) - USD ($)	1 Months Ended						6 Months Ended	12 Months Ended
	Dec. 31, 2016	Apr. 30, 2016	Sep. 30, 2015	Aug. 31, 2015	Jul. 31, 2014	Feb. 29, 2012	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
GlaxoSmithKline (GSK)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from license fees received					$ 6,000,000
Revenue recognized		$ 7,500,000	$ 6,500,000				$ 5,000,000
Term of milestone agreement					3 years
Minimum milestone receivable					$ 5,750,000
Maximum milestone receivable					$ 38,500,000.0
Termination notice period					90 days
License and service revenue								$ 3,000,000	$ 2,000,000
Deferred revenue									3,000,000
Technology Transfer, Collaboration and License Agreement | Merck
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from license fees received				$ 5,000,000
Revenue recognized			$ 5,000,000					8,000,000
Term of milestone agreement				2 years
Potential royalty revenue								15,000,000
License and service revenue								4,000,000	1,000,000
Deferred revenue									4,000,000
Supply Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront milestone payment	$ 750,000
Supply Agreement | Merck
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Term of milestone agreement						5 years
Term of agreement extension						5 years
License and service revenue								1,300,000	1,900,000	$ 2,000,000
Deferred revenue	$ 1,300,000							1,300,000	1,000,000
Merck
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Sales revenue, goods								5,600,000	1,600,000	$ 2,500,000
Collaborative Arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized								$ 1,800,000	$ 1,500,000