Intangible Asset and Goodwill (Details 3) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Components of intangible assets
Accumulated Amortization	$ (241,465)		$ (241,465)		$ (268,534)
Finite-Lived Intangible Assets	28,148		28,148
Indefinite-lived Intangible Assets (Excluding Goodwill)	1,600		1,600
Intangible Assets, Gross (Excluding Goodwill)	271,213		271,213		328,470
Amortization expense for intangible assets	4,900	$ 8,700	9,910	$ 19,269
Intangible Assets, Net	29,748		29,748		59,936
Existing technology
Components of intangible assets
Gross Carrying Amount	234,620		234,620		258,903
Accumulated Amortization	(208,188)		(208,188)		(213,824)
Finite-Lived Intangible Assets	26,432		$ 26,432		$ 45,079
Existing technology | Minimum
Components of intangible assets
Useful Life (in years)			3 years		3 years
Existing technology | Maximum
Components of intangible assets
Useful Life (in years)			10 years		10 years
Customer Contracts [Member]
Components of intangible assets
Gross Carrying Amount	34,693		$ 34,693		$ 67,667
Accumulated Amortization	(32,977)		(32,977)		(54,410)
Finite-Lived Intangible Assets	1,716		$ 1,716		$ 13,257
Customer Contracts [Member] | Minimum
Components of intangible assets
Useful Life (in years)			1 year		1 year
Customer Contracts [Member] | Maximum
Components of intangible assets
Useful Life (in years)			10 years		10 years
Non-compete agreements
Components of intangible assets
Useful Life (in years)			3 years		3 years
Gross Carrying Amount	300		$ 300		$ 300
Accumulated Amortization	(300)		(300)		(300)
Finite-Lived Intangible Assets	0		0		0
Favorable contracts
Components of intangible assets
Finite-Lived Intangible Assets					900
Cash received related to favorable contracts	200	$ 300	700	$ 1,000
In Process Research and Development [Member]
Components of intangible assets
Indefinite-lived Intangible Assets (Excluding Goodwill)	$ 1,600		$ 1,600		$ 1,600