Intangible Assets and Liabilities - Gross Carrying Amount and Accumulated Amortization (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 978,060	$ 769,851	$ 669,896
Intangible assets, gross (excluding goodwill)	981,160	769,851
Accumulated amortization	(723,577)	(674,623)
Finite-lived intangible assets, Net	254,483	95,228
Intangible assets, net	257,583	95,228
Finite-lived intangible liabilities, gross	(23,900)	0	$ 0
Finite-lived intangible liabilities, accumulated accretion	5,217	0
Finite-lived intangible liabilities, net	(18,683)	0
Core-developed technology [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	507,100	429,548
Accumulated amortization	(429,955)	(399,969)
Finite-lived intangible assets, Net	77,145	29,579
Customer contracts and relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	379,614	258,586
Accumulated amortization	(212,538)	(197,582)
Finite-lived intangible assets, Net	167,076	61,004
Trademarks and Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	78,746	70,056
Accumulated amortization	(69,879)	(66,004)
Finite-lived intangible assets, Net	8,867	4,052
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	12,600	11,661
Accumulated amortization	(11,205)	(11,068)
Finite-lived intangible assets, Net	1,395	593
In Process Research and Development [Member]
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets (excluding goodwill)	$ 3,100	$ 0