General and Summary of Significant Accounting Policies Intangible Assets (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Cost	$ 26,672,000	$ 25,682,000
Accumulated Amortization	19,609,000	17,192,000
Net	7,063,000	8,490,000
Amortization [Abstract]
Amortization of Intangible Assets	2,400,000	2,500,000	2,600,000
Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Amortization Life in Years	9 years	9 years
Cost	12,357,000	11,367,000
Accumulated Amortization	7,315,000	6,389,000
Net	5,042,000	4,978,000
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	8,285,000	7,428,000
Net	286,000	1,143,000
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	3,584,000	2,950,000
Net	1,735,000	2,369,000
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	425,000
Net	0	0
Scenario, Forecast [Member]
Amortization [Abstract]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months								1,900,000
Future Amortization Expense, Year Two							1,200,000
Future Amortization Expense, Year Three						1,100,000
Future Amortization Expense, Year Four					1,000,000
Future Amortization Expense, Year Five				$ 600,000