Valuation and Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Allowance for doubtful accounts receivable
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 30	$ 30	$ 30
Charged to cost and expense
Charged to other accounts
Deductions charged to reserves	10
Balance at End of Period	20	30	30
Inventory reserves
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	1,403	989	1,137
Charged to cost and expense	126	450	305
Charged to other accounts
Deductions charged to reserves	1,529	36	453
Balance at End of Period		1,403	989
Warranty reserves
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period
Charged to cost and expense	12
Charged to other accounts
Deductions charged to reserves	2
Balance at End of Period	10
Deferred tax asset valuation allowance
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	40,476	41,759	42,770
Charged to cost and expense
Charged to other accounts		(1,283)	(1,011)
Deductions charged to reserves	40,476
Balance at End of Period		$ 40,476	$ 41,759