Customer, Supplier and Product Concentration - Disaggregation of Revenue by Customer (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Concentration Risk [Line Items]
Revenues, net	$ 120,310	$ 178,057	$ 325,003	$ 343,928
Net Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk percentage	100.00%	100.00%	100.00%	100.00%
Big 3 Wholesalers
Concentration Risk [Line Items]
Revenues, net	$ 71,702	$ 109,355	$ 172,862	$ 206,964
Big 3 Wholesalers | Net Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk percentage	59.60%	61.40%	53.20%	60.20%
Amerisource
Concentration Risk [Line Items]
Revenues, net	$ 22,475	$ 40,275	$ 55,193	$ 70,371
Amerisource | Net Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk percentage	18.70%	22.60%	17.00%	20.50%
Cardinal
Concentration Risk [Line Items]
Revenues, net	$ 19,789	$ 28,337	$ 45,178	$ 58,098
Cardinal | Net Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk percentage	16.40%	15.90%	13.90%	16.90%
McKesson
Concentration Risk [Line Items]
Revenues, net	$ 29,438	$ 40,743	$ 72,491	$ 78,495
McKesson | Net Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk percentage	24.50%	22.90%	22.30%	22.80%
All Others
Concentration Risk [Line Items]
Revenues, net	$ 48,608	$ 68,702	$ 152,141	$ 136,964
All Others | Net Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk percentage	40.40%	38.60%	46.80%	39.80%