Accounts Receivable, Sales and Allowances - Net Trade Accounts Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Gross Accounts Receivable	$ 308,305	$ 378,759	$ 519,175
Less reserves for:
Chargebacks	(55,312)	(73,984)
Rebates	(55,963)	(111,945)
Product returns	(35,146)	(41,687)
Discounts and allowances	(6,561)	(7,779)
Advertising and promotions	(1,574)	(1,301)
Doubtful accounts	(623)	(680)
Trade accounts receivable, net	$ 153,126	$ 141,383