Product Warranties (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Summary of changes in product warranties reserve
Warranty reserve, beginning of period	$ 65,330	$ 65,082	$ 69,787	$ 64,417
Provision	8,041	14,452	11,773	22,673
Payments	(10,567)	(9,353)	(18,756)	(16,909)
Warranty reserve, end of period	$ 62,804	$ 70,181	$ 62,804	$ 70,181