Intangible Assets and Liabilities Gross Carrying Amount and Accumulated Amortization (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Intangible Assets [Line Items]
Intangible assets, Gross	$ 980,619	$ 978,060
Intangible assets, Accumulated (Amortization) Accretion	(743,531)	(723,577)
Intangible assets, Net	237,088	254,483
Intangible assets, Gross	983,519	981,160	$ 1,033,430	$ 769,851
Intangible assets, Net	239,988	257,583
Intangible liabilities, Gross	(23,900)	(23,900)	$ (23,900)	$ 0
Intangible liabilities, Accumulated (Amortization) Accretion	7,275	5,217
Intangible liabilities, Net	(16,625)	(18,683)
Core-developed technology [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	507,023	507,100
Intangible assets, Accumulated (Amortization) Accretion	(436,829)	(429,955)
Intangible assets, Net	70,194	77,145
Customer contracts and relationships [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	382,504	379,614
Intangible assets, Accumulated (Amortization) Accretion	(224,312)	(212,538)
Intangible assets, Net	158,192	167,076
Trademarks and trade names [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	79,071	78,746
Intangible assets, Accumulated (Amortization) Accretion	(71,145)	(69,879)
Intangible assets, Net	7,926	8,867
Other Intangible Assets [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	12,021	12,600
Intangible assets, Accumulated (Amortization) Accretion	(11,245)	(11,205)
Intangible assets, Net	776	1,395
In Process Research and Development [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	2,900	3,100
Intangible assets, Accumulated (Amortization) Accretion	0	0
Intangible assets, Net	$ 2,900	$ 3,100