Product Warranty Reserves (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Product warranty reserves [Roll Forward]
Reserve balance, beginning of the period	$ 11,254	$ 12,258	$ 11,052	$ 12,663
Warranty liabilities accrued	3,507	3,107	6,267	5,849
Warranty liabilities settled	(2,870)	(2,662)	(5,352)	(5,872)
Other	(201)	(69)	(277)	(6)
Reserve balance, end of the period	$ 11,690	$ 12,634	$ 11,690	$ 12,634