Intangible Assets and Liabilities Gross Carrying Amount and Accumulated Amortization (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Intangible Assets [Line Items]
Intangible assets, Accumulated (Amortization) Accretion	$ (877,283)	$ (867,082)
Intangible assets, Net	113,672
Intangible assets, Gross	990,955	1,000,037	$ 952,225	$ 979,814
Intangible assets, Net	113,672	132,955
Intangible liabilities, Gross	(23,900)	(23,900)	$ (23,900)	$ (23,900)
Intangible liabilities, Accumulated (Amortization) Accretion	22,460	21,479
Intangible liabilities, Net	(1,440)	(2,421)
Core-developed technology [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	518,587	525,051
Intangible assets, Accumulated (Amortization) Accretion	(498,890)	(498,113)
Intangible assets, Net	19,697	26,938
Customer contracts and relationships [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	381,112	383,245
Intangible assets, Accumulated (Amortization) Accretion	(290,144)	(280,497)
Intangible assets, Net	90,968	102,748
Trademarks and trade names [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	79,232	79,716
Intangible assets, Accumulated (Amortization) Accretion	(76,620)	(76,912)
Intangible assets, Net	2,612	2,804
Other Intangible Assets [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	12,024	12,025
Intangible assets, Accumulated (Amortization) Accretion	(11,629)	(11,560)
Intangible assets, Net	$ 395	$ 465