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Commitments and Contingencies (Details) (USD $)	12 Months Ended		0 Months Ended
Commitments and Contingencies (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Feb. 17, 2015	Dec. 31, 2012	Dec. 31, 2011
Movement in Standard Product Warranty Accrual [Roll Forward]
Warranty liability balance, beginning of the year	$ 3,328,000us-gaap_StandardProductWarrantyAccrual	$ 3,954,000us-gaap_StandardProductWarrantyAccrual
Product warranty accruals	2,665,000	3,131,000
Adjustments for payments made	(3,393,000)	(3,757,000)
Warranty liability balance, end of the year	2,600,000us-gaap_StandardProductWarrantyAccrual	3,328,000us-gaap_StandardProductWarrantyAccrual
Cash and Cash Equivalents, at Carrying Value	31,242,000	25,482,000		33,182,000	47,770,000
Warranty Reserves
Class of Warrant or Right [Line Items]
Accrued warranty reserve	2,018,000	2,599,000
Warranty Reserves
Class of Warrant or Right [Line Items]
Accrued warranty reserve	582,000	729,000
Subsequent Event \| 2015 Convertible Senior Notes
Movement in Standard Product Warranty Accrual [Roll Forward]
Repayments of convertible debt			$ 18,000,000