Basis of Presentation and Summary of Significant Accounting Policies - Concentration and Significant Customer Information (Details) - facility	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Sales Revenue, Goods, Net | Customer Concentration Risk | AmerisourceBergen Drug Corporation
Concentrations and Significant Customer Information
Concentration risk	22.00%	22.00%
Sales Revenue, Goods, Net | Customer Concentration Risk | McKesson Corporation
Concentrations and Significant Customer Information
Concentration risk	22.00%	14.00%
Accounts Receivable | Customer Concentration Risk | AmerisourceBergen Drug Corporation
Concentrations and Significant Customer Information
Concentration risk	24.00%		27.00%
Accounts Receivable | Customer Concentration Risk | McKesson Corporation
Concentrations and Significant Customer Information
Concentration risk	26.00%		22.00%
Feraheme
Concentrations and Significant Customer Information
Number of production facilities	2