Intangible Assets (Intangible Assets Other Than Goodwill) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Intangible assets with finite lives: Gross	$ 253,357	$ 255,671
Intangible assets with finite lives: Accumulated Amortization	(209,569)	(207,333)
Intangible assets with finite lives: Net	$ 43,788	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	$ 102,920	103,661
Intangible assets with finite lives: Accumulated Amortization	(78,996)	(77,021)
Intangible assets with finite lives: Net	$ 23,924	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	$ 53,665	54,378
Intangible assets with finite lives: Accumulated Amortization	(51,554)	(51,875)
Intangible assets with finite lives: Net	$ 2,111	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	$ 23,397	23,907
Intangible assets with finite lives: Accumulated Amortization	(19,086)	(19,133)
Intangible assets with finite lives: Net	$ 4,311	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	$ 11,974	11,760
Intangible assets with finite lives: Accumulated Amortization	(9,607)	(9,535)
Intangible assets with finite lives: Net	$ 2,367	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	$ 19,530	19,494
Intangible assets with finite lives: Accumulated Amortization	(16,257)	(15,714)
Intangible assets with finite lives: Net	$ 3,273	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	$ 16,207	16,215
Intangible assets with finite lives: Accumulated Amortization	(14,954)	(14,706)
Intangible assets with finite lives: Net	$ 1,253	1,509
Weighted average useful life remaining (in years)	7 years
Other
Finite-Lived Intangible Assets [Line Items]
Intangible assets with finite lives: Gross	$ 25,664	26,256
Intangible assets with finite lives: Accumulated Amortization	(19,115)	(19,349)
Intangible assets with finite lives: Net	$ 6,549	$ 6,907
Weighted average useful life remaining (in years)	1 year