Commitments and Contingencies (Details) (USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Movement in Standard Product Warranty Accrual [Roll Forward]
Warranty liability balance, beginning of the period	$ 3,954,000	$ 3,438,000
Product warranty accruals	2,295,000	3,209,000
Utilization of accrual	(2,835,000)	(3,529,000)
Warranty liability balance, end of the period	3,414,000	3,118,000
Product Warranty Accrual, Current	2,700,000		3,100,000
Product Warranty Accrual, Noncurrent	$ 700,000		$ 800,000