Intangible Assets and Liabilities Gross Carrying Amount and Accumulated Amortization (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Intangible Assets [Line Items]
Intangible assets, Accumulated (Amortization) Accretion	$ (826,760)	$ (794,717)
Intangible assets, Net	144,888
Intangible assets, Gross	971,648	979,814	$ 965,586	$ 981,160
Intangible assets, Net	144,888	185,097
Intangible liabilities, Gross	(23,900)	(23,900)	$ (23,900)	$ (23,900)
Intangible liabilities, Accumulated (Amortization) Accretion	19,472	13,450
Intangible liabilities, Net	(4,428)	(10,450)
Core-developed technology [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	509,222	507,669
Intangible assets, Accumulated (Amortization) Accretion	(476,689)	(458,109)
Intangible assets, Net	32,533	49,560
Customer contracts and relationships [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	372,539	381,288
Intangible assets, Accumulated (Amortization) Accretion	(264,075)	(251,509)
Intangible assets, Net	108,464	129,779
Trademarks and trade names [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	77,864	78,837
Intangible assets, Accumulated (Amortization) Accretion	(74,485)	(73,732)
Intangible assets, Net	3,379	5,105
Other Intangible Assets [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	12,023	12,020
Intangible assets, Accumulated (Amortization) Accretion	(11,511)	(11,367)
Intangible assets, Net	$ 512	$ 653