Collaboration and License Agreements - 2006 Sandoz Collaboration Agreement (Details) - USD ($)			3 Months Ended								12 Months Ended
	Jul. 01, 2017	Jun. 18, 2015	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Oct. 31, 2017	Oct. 04, 2017
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Commercial milestone											$ 10,000,000		$ 20,000,000
Product revenue			$ 13,369,000	$ 10,890,000	$ 19,140,000	$ 23,404,000	$ 15,817,000	$ 23,339,000	$ 20,692,000	$ 14,800,000	66,803,000	$ 74,648,000	48,503,000
Research and development services and external costs											$ 7,064,000	6,620,000	12,133,000
2006 Sandoz Collaboration Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of royalty based on contractually defined profits on sales		50.00%									50.00%
Commercial milestone	$ 10,000,000										$ 10,000,000		20,000,000
Milestone payments, no longer eligible to earn, commercial milestone														$ 80,000,000
Amount of cost of goods to be deducted from share of defined profits due to milestone not being met															$ 9,800,000
Product revenue											66,490,000	74,648,000	43,440,000
Research and development services and external costs											$ 2,142,000	$ 2,545,000	$ 2,861,000
Novartis Pharma AG | 2006 Sandoz Collaboration Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of contractual profits earned under collaborative arrangement											50.00%
Maximum | 2006 Sandoz Collaboration Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments possible per agreement														$ 30,000,000