Basis of Presentation and Summary of Significant Accounting Policies - Concentration and Significant Customer Information (Details) - facility	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Sales Revenue, Goods, Net | Customer Concentration Risk | AmerisourceBergen Drug Corporation
Concentrations and Significant Customer Information
Concentration risk	27.00%	23.00%	27.00%	25.00%
Sales Revenue, Goods, Net | Customer Concentration Risk | McKesson Corporation
Concentrations and Significant Customer Information
Concentration risk	26.00%	26.00%	27.00%	22.00%
Accounts Receivable | Customer Concentration Risk | AmerisourceBergen Drug Corporation
Concentrations and Significant Customer Information
Concentration risk			29.00%		31.00%
Accounts Receivable | Customer Concentration Risk | McKesson Corporation
Concentrations and Significant Customer Information
Concentration risk			27.00%		26.00%
Feraheme
Concentrations and Significant Customer Information
Number of production facilities			2