Acquisitions - Weighted-average Useful Lives of Acquired Other Intangible Assets (Detail) (Other Identifiable Intangibles, Customer Contracts And Relationships)	0 Months Ended
	Nov. 01, 2012	Oct. 01, 2014	Aug. 01, 2014	Mar. 01, 2014	May 01, 2012	Aug. 01, 2013	Sep. 01, 2013
Air Serv
Business Acquisition [Line Items]
Weighted-average amortization period for the acquired intangible assets	14 years
HHA
Business Acquisition [Line Items]
Weighted-average amortization period for the acquired intangible assets	13 years
GBM
Business Acquisition [Line Items]
Weighted-average amortization period for the acquired intangible assets		10 years
Airco
Business Acquisition [Line Items]
Weighted-average amortization period for the acquired intangible assets			12 years
Alpha
Business Acquisition [Line Items]
Weighted-average amortization period for the acquired intangible assets				9 years
Calvert-Jones
Business Acquisition [Line Items]
Weighted-average amortization period for the acquired intangible assets	12 years
TEGG
Business Acquisition [Line Items]
Weighted-average amortization period for the acquired intangible assets					14 years
Blackjack
Business Acquisition [Line Items]
Weighted-average amortization period for the acquired intangible assets						11 years
BEST
Business Acquisition [Line Items]
Weighted-average amortization period for the acquired intangible assets							9 years