Trade Accounts Receivable, net (Details) (USD $) In Thousands, unless otherwise specified			12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Trade accounts receivable Largest customer
Trade Accounts Receivable, net
Trade accounts receivable	$ 85,732	$ 78,642
Allowance for doubtful accounts	(1,288)	(991)
Allowance for sales discounts	(1,632)	(1,231)
Trade accounts receivable, net	$ 82,812	$ 76,420
Trade accounts receivable, net
Percentage of trade accounts receivable from the largest customer			12.00%