Goodwill and Other Intangible Assets (Weighted Average Amortization Period by Intangible Asset Class) (Detail)	12 Months Ended
	Dec. 31, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	8 years 3 months 18 days
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	9 years 7 months 6 days
Technology
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	5 years 4 months 24 days
Trademarks and patents
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	6 years 6 months
Covenant not to compete
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	2 years 6 months