Trade Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Receivables [Abstract]
Trade accounts receivable	$ 186,219	$ 149,886	$ 197,378
Allowance for doubtful accounts	(1,434)	(1,364)	(1,312)
Allowance for sales discounts and returns	(3,887)	(2,470)	(3,085)
Trade accounts receivable, net	$ 180,898	$ 146,052	$ 192,981