Trade Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Receivables [Abstract]
Trade accounts receivable	$ 136,748	$ 95,033	$ 131,323
Allowance for doubtful accounts	(919)	(929)	(836)
Allowance for sales discounts and returns	(3,102)	(2,089)	(2,992)
Trade accounts receivable, net	$ 132,727	$ 92,015	$ 127,495