Gross-to-Net Product Sales and Significant Customers - Reconciliation of Gross-to-Net Product Sales (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Product sales, net	$ 29,402	$ 25,268	$ 24,168	$ 30,495	$ 28,570	$ 36,395	$ 34,301	$ 29,101	$ 109,333	$ 128,367	$ 146,444
Product [Member]
Disaggregation of Revenue [Line Items]
Gross product sales									190,825	245,797	244,770
Commercial rebates and government chargebacks									(68,976)	(105,148)	(98,317)
Data and distribution fees, GPO fees, and inventory management fees									(14,048)	(20,083)	(14,979)
Prompt pay discounts									(1,553)	(1,610)	(755)
Product returns									(1,782)	(2,778)	(2,123)
Product sales, net									$ 104,466	$ 116,178	$ 128,596
Gross product sales, percentage of net revenue
Commercial rebates and government chargebacks, percentage of net revenue									(36.10%)	(42.80%)	(40.20%)
Data and distribution fees, GPO fees, and inventory management fees, percentage of net revenue									(7.40%)	(8.20%)	(6.10%)
Prompt pay discounts, percentage of net revenue									(0.80%)	(0.70%)	(0.30%)
Product returns, percentage of net revenue									(0.90%)	(1.10%)	(0.90%)
Product sales, net, percentage of net revenue									54.70%	47.30%	52.50%