Goodwill and Other Intangible Assets - Schedule of Other Intangible Assets Additions by Component (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Schedule Of Other Intangible Assets [Line Items]
Additions to other intangible assets	$ 14.1	$ 5.2
Customer Relationships
Schedule Of Other Intangible Assets [Line Items]
Additions to other intangible assets, Amount	$ 11.0	$ 4.9
Weighted Average Amortization Period	10 years 6 months	9 years 2 months 12 days
Trade Names
Schedule Of Other Intangible Assets [Line Items]
Additions to other intangible assets, Amount	$ 1.4
Weighted Average Amortization Period	4 years 8 months 12 days	0 years
Non-Compete Agreements
Schedule Of Other Intangible Assets [Line Items]
Additions to other intangible assets, Amount	$ 1.7	$ 0.3
Weighted Average Amortization Period	3 years 3 months 18 days	4 years 3 months 18 days