Revenue Recognition - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Adjustments related to prior period sales. Medicaid rebates	$ 6,531	$ 8,603	$ 15,100
Adjustments related to prior period sales, contractual adjustments	2,660	1,540	4,200
Deferred revenue	6,300	6,400	6,300
Current portion of deferred revenue	1,128		1,128	$ 0
Perosphere Pharmaceuticals Inc.
Disaggregation of Revenue [Line Items]
Potential milestone payment receivable		$ 34,800
Potential milestone payment receivable, subject to FDA clearance	$ 34,800		$ 34,800