Commitments (Details) (USD $)	12 Months Ended						12 Months Ended		36 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Capital Lease Obligations [Member]	Dec. 31, 2011 Capital Lease Obligations [Member]	Dec. 31, 2012 Property [Member]	Dec. 31, 2012 Property [Member] Capital Lease Obligations [Member]	Dec. 31, 1996 Property [Member] Capital Lease Obligations [Member]	Mar. 31, 2011 Property [Member] Capital Lease Obligations [Member]	Dec. 31, 2012 Equipment [Member]
Property Subject to or Available for Operating Lease [Line Items]
Term of lease								20 years
Capital leased property	$ 14,148,000	$ 14,065,000						$ 12,300,000
Capital lease obligations								12,300,000
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments, Fiscal Year Maturity [Abstract]
2013	2,098,000					2,064,000				34,000
2014	2,097,000					2,064,000				33,000
2015	2,093,000					2,063,000				30,000
2016	517,000					516,000				1,000
2017	1,000					0				1,000
Total minimum obligations	6,806,000					6,707,000				99,000
Less amounts representing interest (ranging from 4.4% to 17.4%)	(1,762,000)					(1,760,000)				(2,000)
Net present value of minimum obligations	5,044,000					4,947,000				97,000
Less current portion	(1,241,000)	(1,033,000)				(1,208,000)				(33,000)
Long-term capital lease obligations at December 31, 2012	3,803,000	4,948,000				3,739,000				64,000
Interest rate percentage, minimum (in hundredths)				4.40%
Interest rate percentage, maximum (in hundredths)				17.40%
Period when rent is subject to adjustments							3 years
Increase in monthly rental payments							7,000
Monthly rental payments of leased property							172,000		165,000
Accumulated amortization for property and equipment under capital leases				11,700,000	11,100,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2013	679,000
2014	512,000
2015	523,000
2016	382,000
2017	267,000
Remainder	1,806,000
Total minimum lease payments	4,169,000
Rent expense charged to operations	1,100,000	1,200,000	1,200,000
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
Balance Beginning of Year	953,000	1,079,000	1,708,000
Accruals	(393,000)	257,000	(341,000)
Warranty Expenses	(334,000)	(383,000)	(288,000)
Balance End of Year	$ 226,000	$ 953,000	$ 1,079,000