Intangible Assets by Major Class (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Goodwill And Intangible Assets [Line Items]
Finite lived intangible assets, Gross Carrying Amount	$ 139,408	$ 149,831
Intangible assets, Accumulated Amortization	81,073	78,397
Intangible assets, Gross Carrying Amount	145,008	155,431
Customer Relationships
Goodwill And Intangible Assets [Line Items]
Finite lived intangible assets, Gross Carrying Amount	128,512	136,692
Intangible assets, Accumulated Amortization	72,941	69,472
Non-Competition agreements
Goodwill And Intangible Assets [Line Items]
Finite lived intangible assets, Gross Carrying Amount	7,263	9,167
Intangible assets, Accumulated Amortization	7,052	8,275
Software
Goodwill And Intangible Assets [Line Items]
Finite lived intangible assets, Gross Carrying Amount	3,273	3,594
Intangible assets, Accumulated Amortization	$ 940	613
Minimum
Goodwill And Intangible Assets [Line Items]
Finite lived intangible assets, Useful Life in Years	1 year
Minimum | Customer Relationships
Goodwill And Intangible Assets [Line Items]
Finite lived intangible assets, Useful Life in Years	1 year
Minimum | Non-Competition agreements
Goodwill And Intangible Assets [Line Items]
Finite lived intangible assets, Useful Life in Years	1 year
Minimum | Software
Goodwill And Intangible Assets [Line Items]
Finite lived intangible assets, Useful Life in Years	3 years
Maximum
Goodwill And Intangible Assets [Line Items]
Finite lived intangible assets, Useful Life in Years	15 years
Maximum | Customer Relationships
Goodwill And Intangible Assets [Line Items]
Finite lived intangible assets, Useful Life in Years	15 years
Maximum | Non-Competition agreements
Goodwill And Intangible Assets [Line Items]
Finite lived intangible assets, Useful Life in Years	10 years
Maximum | Software
Goodwill And Intangible Assets [Line Items]
Finite lived intangible assets, Useful Life in Years	10 years
Trade Names
Goodwill And Intangible Assets [Line Items]
Finite lived intangible assets, Gross Carrying Amount	$ 360	378
Intangible assets, Accumulated Amortization	$ 140	37
Indefinite-lived intangible assets, Useful Life	Indefinite
Indefinite-lived intangible assets, Gross Carrying Amount	$ 5,600	$ 5,600
Trade Names | Minimum
Goodwill And Intangible Assets [Line Items]
Finite lived intangible assets, Useful Life in Years	1 year
Trade Names | Maximum
Goodwill And Intangible Assets [Line Items]
Finite lived intangible assets, Useful Life in Years	2 years