Intangible Assets and Liabilities Gross Carrying Amount and Accumulated Amortization (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Intangible Assets [Line Items]
Intangible assets, Gross	$ 993,438	$ 769,851
Intangible assets, Accumulated (Amortization) Accretion	(718,346)	(674,623)
Intangible assets, Net	275,092	95,228
Intangible assets, Gross	996,538	769,851	$ 764,036	$ 669,896
Intangible assets, Net	278,192	95,228
Intangible liabilities, Gross	(23,900)	0	$ 0	$ 0
Intangible liabilities, Accumulated (Amortization) Accretion	3,913	0
Intangible liabilities, Net	(19,987)	0
Core-developed technology [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	515,949	429,548
Intangible assets, Accumulated (Amortization) Accretion	(427,069)	(399,969)
Intangible assets, Net	88,880	29,579
Customer contracts and relationships [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	385,148	258,586
Intangible assets, Accumulated (Amortization) Accretion	(210,735)	(197,582)
Intangible assets, Net	174,413	61,004
Trademarks and trade names [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	79,739	70,056
Intangible assets, Accumulated (Amortization) Accretion	(69,376)	(66,004)
Intangible assets, Net	10,363	4,052
Other Intangible Assets [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	12,602	11,661
Intangible assets, Accumulated (Amortization) Accretion	(11,166)	(11,068)
Intangible assets, Net	1,436	593
In Process Research and Development [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	3,100	0
Intangible assets, Accumulated (Amortization) Accretion	0	0
Intangible assets, Net	$ 3,100	$ 0