Summary of Significant Accounting Policies Intangible Assets (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Cost	$ 25,682,000	$ 24,602,000
Accumulated Amortization	17,192,000	14,650,000
Net	8,490,000	9,952,000
Amortization [Abstract]
Amortization of Intangible Assets	2,500,000	2,600,000	2,700,000
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months								2,400,000
Future Amortization Expense, Year Two							1,700,000
Future Amortization Expense, Year Three						1,100,000
Future Amortization Expense, Year Four					1,000,000
Future Amortization Expense, Year Five				900,000
Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Amortization Life in Years	9 years	9 years
Cost	11,367,000	10,287,000
Accumulated Amortization	6,389,000	5,350,000
Net	4,978,000	4,937,000
MCDA contract [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Amortization Life in Years	10 years	10 years
Cost	8,571,000	8,571,000
Accumulated Amortization	7,428,000	6,571,000
Net	1,143,000	2,000,000
Customer Contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Amortization Life in Years	9 years	9 years
Cost	5,319,000	5,319,000
Accumulated Amortization	2,950,000	2,317,000
Net	2,369,000	3,002,000
Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Amortization Life in Years	4 years	4 years
Cost	425,000	425,000
Accumulated Amortization	425,000	412,000
Net	$ 0	$ 13,000