Summary of Significant Accounting Policies Intangible Assets (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Finite-Lived Intangible Assets [Abstract]
Cost	$ 23,457,000	$ 25,375,000
Accumulated Amortization	12,038,000	10,569,000
Net	11,419,000	14,806,000
Amortization [Abstract]
Amortization of Intangible Assets	2,700,000	2,800,000	2,300,000
Future Amortization Expense, Year One	2,600,000
Future Amortization Expense, Year Two	2,400,000
Future Amortization Expense, Year Three	2,100,000
Future Amortization Expense, Year Four	1,400,000
Future Amortization Expense, Year Five	900,000
Patents [Member]
Finite-Lived Intangible Assets [Abstract]
Weighted-Average Amortization Life in Years	9	9
Cost	9,142,000	11,060,000
Accumulated Amortization	4,335,000	4,463,000
Net	4,807,000	6,597,000
MCDA contract [Member]
Finite-Lived Intangible Assets [Abstract]
Weighted-Average Amortization Life in Years	10	10
Cost	8,571,000	8,571,000
Accumulated Amortization	5,714,000	4,857,000
Net	2,857,000	3,714,000
Customer Contracts [Member]
Finite-Lived Intangible Assets [Abstract]
Weighted-Average Amortization Life in Years	9	9
Cost	5,319,000	5,319,000
Accumulated Amortization	1,684,000	1,050,000
Net	3,635,000	4,269,000
Trademarks [Member]
Finite-Lived Intangible Assets [Abstract]
Weighted-Average Amortization Life in Years	4	4
Cost	425,000	425,000
Accumulated Amortization	305,000	199,000
Net	$ 120,000	$ 226,000