Accounts Receivable, Sales and Allowances - Summary of Adjustments to Gross Sales (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Receivables [Abstract]
Gross sales	$ 2,351,071	$ 2,891,267	$ 2,511,693
Less adjustments for:
Chargebacks	(953,326)	(1,218,560)	(1,065,244)
Rebates, administrative fees and others	(476,601)	(463,724)	(367,514)
Product returns	(26,874)	(28,285)	(34,272)
Discounts and allowances	(45,292)	(55,494)	(50,384)
Advertising, promotions, and others	(7,933)	(8,361)	(9,203)
Revenues, net	$ 841,045	$ 1,116,843	$ 985,076