Commitments and Contingencies - (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011	Dec. 31, 2010
Commitments and Contingencies [Abstract]
Standard Product Warranty Accrual	$ 1,509	$ 1,747	$ 1,406	$ 1,654
Product Warranty Accrual, Warranties Issued	1,033	1,216
Product Warranty Accrual, Additions from Business Acquisition	93	0
Product Warranty Accrual, Payments	$ (1,023)	$ (1,123)