Balance Sheet Account Detail - Schedule of Amounts Presented in Accounts Payable and Other Accrued Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Commercial/Medicaid Rebates and Government Chargebacks [Member]
Accounts Payable and Other Liabilities [Roll Forward]
Beginning balance	$ 11,101	$ 10,358
Add: GTN accruals recorded for product sales	5,452	65,751
(Less): Payments made and credits against GTN accruals	(8,998)	(65,008)
Ending balance	7,555	11,101
Distribution, Data, Inventory and GPO Administrative Fees [Member]
Accounts Payable and Other Liabilities [Roll Forward]
Beginning balance	3,932	5,727
Add: GTN accruals recorded for product sales	12	13,962
(Less): Payments made and credits against GTN accruals	(1,028)	(15,757)
Ending balance	2,916	3,932
Product Return Allowances [Member]
Accounts Payable and Other Liabilities [Roll Forward]
Beginning balance	5,171	4,045
Add: GTN accruals recorded for product sales	167	1,700
(Less): Payments made and credits against GTN accruals	(13)	(574)
Ending balance	$ 5,325	$ 5,171