Trade Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Receivables [Abstract]
Trade accounts receivable	$ 139,198	$ 109,859	$ 120,701
Allowance for doubtful accounts	(918)	(1,142)	(765)
Allowance for sales discounts and returns	(3,157)	(2,706)	(2,620)
Trade accounts receivable, net	$ 135,123	$ 106,011	$ 117,316