Intangible Assets and Liabilities - Gross Carrying Amount and Accumulated Amortization (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 1,000,037	$ 979,814	$ 981,160
Intangible assets, gross (excluding goodwill)	1,000,037	979,814
Accumulated amortization	(867,082)	(794,717)
Finite-lived intangible assets, Net	132,955	185,097
Intangible assets, net	132,955	185,097
Finite-lived intangible liabilities, gross	(23,900)	(23,900)	(23,900)
Finite-lived intangible liabilities, accumulated accretion	21,479	13,450
Finite-lived intangible liabilities, net	(2,421)	(10,450)
Amortization of intangible assets	44,711	64,286	$ 71,713
Core-developed technology [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	525,051	507,669
Accumulated amortization	(498,113)	(458,109)
Finite-lived intangible assets, Net	26,938	49,560
Customer contracts and relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	383,245	381,288
Accumulated amortization	(280,497)	(251,509)
Finite-lived intangible assets, Net	102,748	129,779
Trademarks and Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	79,716	78,837
Accumulated amortization	(76,912)	(73,732)
Finite-lived intangible assets, Net	2,804	5,105
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	12,025	12,020
Accumulated amortization	(11,560)	(11,367)
Finite-lived intangible assets, Net	$ 465	$ 653