Intangible Assets and Goodwill (Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Finite lived intangible assets
Gross Carrying Amount	$ 689,620		$ 686,095
Accumulated Amortization	(466,615)		(458,958)
Net Carrying Amount	223,005		227,137
Amortization expense	10,000	$ 11,000
Customer relationships
Finite lived intangible assets
Gross Carrying Amount	484,543		480,837
Accumulated Amortization	(286,393)		(281,190)
Net Carrying Amount	198,150		199,647
Software & technology
Finite lived intangible assets
Gross Carrying Amount	164,973		165,088
Accumulated Amortization	(145,518)		(143,877)
Net Carrying Amount	19,455		21,211
Trademarks & other
Finite lived intangible assets
Gross Carrying Amount	40,104		40,170
Accumulated Amortization	(34,704)		(33,891)
Net Carrying Amount	$ 5,400		$ 6,279

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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