Interest (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summarized of interest incurred, capitalized and paid as well as the amortization of capitalized interest
Interest incurred	$ 3,334	$ 2,860	$ 2,696
Less capitalized interest	(200)	(48)	(31)
Total net expense	3,134	2,812	2,665
Interest paid	2,639	2,211	2,225
Amortization of capitalized interest included in cost of sales	$ 336	$ 441	$ 499