Goodwill and Intangible Assets (Weighted Average Amortization Period by Intangible Asset Class) (Details)	9 Months Ended
	Sep. 30, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period	6 years 8 months
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period	7 years 8 months
Technology
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period	4 years 5 months
Trademarks and trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period	5 years 1 month
Covenants not to compete
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period	2 years 3 months