Trade Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Receivables [Abstract]
Trade accounts receivable	$ 144,935	$ 95,033	$ 141,565
Allowance for doubtful accounts	(829)	(929)	(936)
Allowance for sales discounts and returns	(3,161)	(2,089)	(2,826)
Trade accounts receivable, net	$ 140,945	$ 92,015	$ 137,803