Basis of Presentation (Finite-Lived Intangible Assets by Major Class) (Details)	12 Months Ended
	Dec. 31, 2018
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, amortization method	Straight-line and accelerated	[1]
Customer relationships [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, useful life	4 years
Customer relationships [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, useful life	17 years
Marketing assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, amortization method	Straight-line
Marketing assets [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, useful life	1 year
Marketing assets [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, useful life	15 years
Acquired software and technology [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, amortization method	Straight-line and accelerated
Acquired software and technology [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, useful life	1 year
Acquired software and technology [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, useful life	11 years
Non-compete agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, amortization method	Straight-line
Non-compete agreements [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, useful life	1 year
Non-compete agreements [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, useful life	5 years
Database [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, amortization method	Straight-line
Finite-lived intangible assets, useful life	8 years

[1] Certain of the customer relationships and acquired software and technology assets are amortized on an accelerated basis.