Intangible Assets and Liabilities Gross Carrying Amount and Accumulated Amortization (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Intangible Assets [Line Items]
Intangible assets, Accumulated (Amortization) Accretion	$ (795,100)	$ (794,717)
Intangible assets, Net	157,125
Intangible assets, Gross	952,225	979,814	$ 985,509	$ 981,160
Intangible assets, Net	157,125	185,097
Intangible liabilities, Gross	(23,900)	(23,900)	$ (23,900)	$ (23,900)
Intangible liabilities, Accumulated (Amortization) Accretion	17,465	13,450
Intangible liabilities, Net	(6,435)	(10,450)
Core-developed technology [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	498,006	507,669
Intangible assets, Accumulated (Amortization) Accretion	(459,876)	(458,109)
Intangible assets, Net	38,130	49,560
Customer contracts and relationships [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	365,567	381,288
Intangible assets, Accumulated (Amortization) Accretion	(251,085)	(251,509)
Intangible assets, Net	114,482	129,779
Trademarks and trade names [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	76,631	78,837
Intangible assets, Accumulated (Amortization) Accretion	(72,677)	(73,732)
Intangible assets, Net	3,954	5,105
Other Intangible Assets [Member]
Intangible Assets [Line Items]
Intangible assets, Gross	12,021	12,020
Intangible assets, Accumulated (Amortization) Accretion	(11,462)	(11,367)
Intangible assets, Net	$ 559	$ 653