Goodwill and Intangible Assets (Weighted Average Amortization Period by Intangible Asset Class) (Details)	6 Months Ended
	Jun. 30, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period	7 years 8 months 12 days
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period	8 years 11 months
Technology
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period	4 years 9 months 18 days
Trademarks and trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period	5 years 11 months
Covenants not to compete
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period	1 year 8 months