Goodwill and Other Intangible Assets - Narrative (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Goodwill and Other Intangible Assets [Line Items]
Additions to goodwill			$ 0
Amortization expense of intangible assets	$ 2,200,000	$ 2,300,000	$ 4,500,000	$ 4,400,000
Customer relationships
Goodwill and Other Intangible Assets [Line Items]
Amortization period of intangible assets, in years			15 years
Non-compete agreements
Goodwill and Other Intangible Assets [Line Items]
Amortization period of intangible assets, in years			5 years
Other intangible assets
Goodwill and Other Intangible Assets [Line Items]
Amortization period of intangible assets, in years			15 years