Goodwill and Other Intangible Assets - Schedule of Other Intangible Assets Additions by Component (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Schedule Of Other Intangible Assets [Line Items]
Additions to other intangible assets	$ 14.1
Client Relationships
Schedule Of Other Intangible Assets [Line Items]
Additions to other intangible assets, Amount	$ 11.0
Weighted Average Amortization Period	10 years 6 months
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
Non-Compete Agreements
Schedule Of Other Intangible Assets [Line Items]
Additions to other intangible assets, Amount	$ 1.7
Weighted Average Amortization Period	3 years 3 months 18 days