Intangible Assets Finite-Lived Intangible Assets by Major Class (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 171,889,000	$ 171,889,000
Finite-Lived Intangible Assets, Accumulated Amortization	(141,567,000)	(128,665,000)
Total estimated future amortization expense	30,322,000	43,224,000
Amortization of Intangible Assets	$ 12,900,000	13,300,000	$ 13,800,000
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	1 year
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	8 years
Purchased Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 114,754,000	114,754,000
Finite-Lived Intangible Assets, Accumulated Amortization	(95,260,000)	(87,398,000)
Total estimated future amortization expense	19,494,000	27,356,000
Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	6,472,000	6,472,000
Finite-Lived Intangible Assets, Accumulated Amortization	(6,472,000)	(6,472,000)
Total estimated future amortization expense	0	0
Customer Lists [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	37,000,000	37,000,000
Finite-Lived Intangible Assets, Accumulated Amortization	(30,534,000)	(26,284,000)
Total estimated future amortization expense	6,466,000	10,716,000
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	11,536,000	11,536,000
Finite-Lived Intangible Assets, Accumulated Amortization	(7,174,000)	(6,384,000)
Total estimated future amortization expense	4,362,000	5,152,000
Order or Production Backlog [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	2,127,000	2,127,000
Finite-Lived Intangible Assets, Accumulated Amortization	(2,127,000)	(2,127,000)
Total estimated future amortization expense	$ 0	$ 0