Acquisitions, Intangible Assets and Goodwill (Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Finite lived intangible assets
Gross Carrying Amount	$ 746,043		$ 741,795
Accumulated Amortization	(484,725)		(469,609)
Net Carrying Amount	261,318		272,186
Amortization expense	11,000	$ 8,000
Customer relationships
Finite lived intangible assets
Gross Carrying Amount	528,997		526,149
Accumulated Amortization	(303,449)		(292,500)
Net Carrying Amount	225,548		233,649
Software & technology
Finite lived intangible assets
Gross Carrying Amount	174,208		173,141
Accumulated Amortization	(147,595)		(144,742)
Net Carrying Amount	26,613		28,399
Trademarks & other
Finite lived intangible assets
Gross Carrying Amount	42,838		42,505
Accumulated Amortization	(33,681)		(32,367)
Net Carrying Amount	$ 9,157		$ 10,138