Accrued Liabilities Accrued rebates, chargebacks and other reserves (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Discount and Distribution Fees	$ 3,422	$ 2,475
Government rebates and chargebacks	8,709	5,514
Assistance and Other Discounts	4,178	2,580
Product return	3,304	1,769
Accrued liabilities, amounts received in advance of revenue recognition	$ 19,613	$ 12,338