Summary of Significant Accounting Policies - Customers Who Represent 10% or More of Total Revenues or Accounts Receivable Balances (Details) - facility	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Sales Revenue, Goods, Net | Customer Concentration Risk | AmerisourceBergen Drug Corporation
Concentrations and Significant Customer Information
Concentration risk, including less than and more than 10% (percent)	27.00%	26.00%	27.00%
Sales Revenue, Goods, Net | Customer Concentration Risk | McKesson Corporation
Concentrations and Significant Customer Information
Concentration risk, including less than and more than 10% (percent)	26.00%	24.00%	14.00%
Sales Revenue, Goods, Net | Customer Concentration Risk | Caremark, LLC
Concentrations and Significant Customer Information
Concentration risk, including less than and more than 10% (percent)	10.00%	10.00%	10.00%
Accounts Receivable | Customer Concentration Risk | Three Customers
Concentrations and Significant Customer Information
Concentration risk, including less than and more than 10% (percent)	73.00%
Accounts Receivable | Customer Concentration Risk | Two Customers
Concentrations and Significant Customer Information
Concentration risk, including less than and more than 10% (percent)		57.00%
Feraheme
Concentrations and Significant Customer Information
Number of production facilities	2