Commitments and Contingencies (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Commitments and Contingencies Disclosure [Abstract]
Rental expense for operating leases	$ 2,088	$ 1,879	$ 1,632
Purchase obligations	76,338
Environmental reserve	$ 1,185
Period for monitoring contamination (years)	30 years