Acquisitions, Intangible Assets and Goodwill (Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Finite lived intangible assets
Gross Carrying Amount	$ 687,426		$ 687,426		$ 712,487
Accumulated Amortization	(449,259)		(449,259)		(440,301)
Net Carrying Amount	238,167		238,167		272,186
Amortization expense	11,000	$ 8,000	33,000	$ 24,000
Customer relationships
Finite lived intangible assets
Gross Carrying Amount	481,422		481,422		504,716
Accumulated Amortization	(273,388)		(273,388)		(271,066)
Net Carrying Amount	208,034		208,034		233,650
Software & technology
Finite lived intangible assets
Gross Carrying Amount	165,692		165,692		167,122
Accumulated Amortization	(142,747)		(142,747)		(138,724)
Net Carrying Amount	22,945		22,945		28,398
Trademarks & other
Finite lived intangible assets
Gross Carrying Amount	40,312		40,312		40,649
Accumulated Amortization	(33,124)		(33,124)		(30,511)
Net Carrying Amount	$ 7,188		$ 7,188		$ 10,138