Intangible Assets Gross Carrying Amount and Accumulated Amortization (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Intangible Assets [Line Items]
Gross Assets	$ 763,326	$ 669,896		$ 702,507
Accumulated Amortization	(663,747)	(597,745)
Intangible Assets, Net (Excluding Goodwill)	100,289	72,151
Net Assets	99,579	72,151
Intangible Assets, Gross (Excluding Goodwill)	764,036		$ 704,816
Core-developed technology [Member]
Intangible Assets [Line Items]
Gross Assets	425,198	372,568
Accumulated Amortization	(393,831)	(354,878)
Net Assets	31,367	17,690
Customer contracts and relationships [Member]
Intangible Assets [Line Items]
Gross Assets	256,840	224,467
Accumulated Amortization	(193,317)	(170,056)
Net Assets	63,523	54,411
Trademarks and trade names [Member]
Intangible Assets [Line Items]
Gross Assets	69,706	61,785
Accumulated Amortization	(65,537)	(61,766)
Net Assets	4,169	19
Other Intangible Assets [Member]
Intangible Assets [Line Items]
Gross Assets	11,582	11,076
Accumulated Amortization	(11,062)	(11,045)
Net Assets	520	31
In Process Research and Development [Member]
Intangible Assets [Line Items]
Gross Assets	710	0
Accumulated Amortization	0	0
Net Assets	$ 710	$ 0