Intangible Assets (Intangible Assets Other Than Goodwill) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Intangible assets with finite lives: Gross	$ 259,589	$ 255,671
Intangible assets with finite lives: Accumulated Amortization	(222,701)	(207,333)
Intangible assets with finite lives: Net	$ 36,888	48,338
Weighted average useful life remaining (in years)	5 years
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets with finite lives: Gross	$ 106,098	103,661
Intangible assets with finite lives: Accumulated Amortization	(86,068)	(77,021)
Intangible assets with finite lives: Net	$ 20,030	26,640
Weighted average useful life remaining (in years)	4 years
Acquired technology
Finite-Lived Intangible Assets [Line Items]
Intangible assets with finite lives: Gross	$ 54,795	54,378
Intangible assets with finite lives: Accumulated Amortization	(53,329)	(51,875)
Intangible assets with finite lives: Net	$ 1,466	2,503
Weighted average useful life remaining (in years)	1 year
Trade names
Finite-Lived Intangible Assets [Line Items]
Intangible assets with finite lives: Gross	$ 23,754	23,907
Intangible assets with finite lives: Accumulated Amortization	(20,224)	(19,133)
Intangible assets with finite lives: Net	$ 3,530	4,774
Weighted average useful life remaining (in years)	4 years
Patent costs
Finite-Lived Intangible Assets [Line Items]
Intangible assets with finite lives: Gross	$ 19,112	11,760
Intangible assets with finite lives: Accumulated Amortization	(10,345)	(9,535)
Intangible assets with finite lives: Net	$ 8,767	2,225
Weighted average useful life remaining (in years)	15 years
Trade secrets
Finite-Lived Intangible Assets [Line Items]
Intangible assets with finite lives: Gross	$ 19,857	19,494
Intangible assets with finite lives: Accumulated Amortization	(17,535)	(15,714)
Intangible assets with finite lives: Net	$ 2,322	3,780
Weighted average useful life remaining (in years)	2 years
Acquired patents
Finite-Lived Intangible Assets [Line Items]
Intangible assets with finite lives: Gross	$ 16,266	16,215
Intangible assets with finite lives: Accumulated Amortization	(15,498)	(14,706)
Intangible assets with finite lives: Net	$ 768	1,509
Weighted average useful life remaining (in years)	7 years
Other
Finite-Lived Intangible Assets [Line Items]
Intangible assets with finite lives: Gross	$ 19,707	26,256
Intangible assets with finite lives: Accumulated Amortization	(19,702)	(19,349)
Intangible assets with finite lives: Net	$ 5	$ 6,907
Weighted average useful life remaining (in years)	1 year