Acquisitions - Final Purchase Price and Related Allocations (Detail) (USD $) In Millions, unless otherwise specified					0 Months Ended			0 Months Ended			0 Months Ended			0 Months Ended			0 Months Ended				0 Months Ended
	Jul. 31, 2014	Oct. 31, 2013	Nov. 01, 2012 Purchase Price Allocation	Nov. 01, 2012 Air Serv	Nov. 01, 2012 Air Serv Purchase Price Allocation	Nov. 01, 2012 Air Serv Purchase Price Allocation		Nov. 01, 2012 HHA Purchase Price Allocation	Nov. 01, 2012 HHA Purchase Price Allocation		Mar. 01, 2014 Alpha Mechanical, Inc. Purchase Price Allocation	Mar. 01, 2014 Alpha Mechanical, Inc. Purchase Price Allocation		Nov. 01, 2012 Calvert-Jones Purchase Price Allocation	Nov. 01, 2012 Calvert-Jones Purchase Price Allocation		Aug. 01, 2013 Blackjack Purchase Price Allocation	Aug. 01, 2013 Blackjack Purchase Price Allocation		Sep. 01, 2013 BEST	Sep. 01, 2013 BEST Purchase Price Allocation	Sep. 01, 2013 BEST Purchase Price Allocation
Purchase price:
Cash consideration					$ 162.9			$ 33.7			$ 12.3			$ 6.1			$ 5.2				$ 2.9
Fair value of contingent consideration liability					0			0			0			0			0				1.6
Holdback liability			0			0			0			0						0				0.4
Total consideration					162.9			33.7			12.3			6.1			5.2				4.9
Allocated to:
Trade accounts receivable (1)						52.7	[1]		3.2	[1]		3.4	[1]		1.4	[1]		4.6	[1]			1.2	[1]
Other current and noncurrent assets						16.2			2.2			1.4			0.3			0.2				0
Property, plant and equipment						16.7			0.1			0.5			0.1			0.3				0.6
Other intangible assets (2)						44.6	[2]		15.0	[2]		3.3	[2]		2.6	[2]		0.9	[2]			1.4	[2]
Goodwill (3)	879.1	872.4				88.8	[3]		23.8	[3]		6.8	[3]		4.0	[3]		1.8	[3]			1.9	[3]
Total assets acquired						219.0			44.3			15.4			8.4			7.8				5.1
Liabilities assumed						(56.1)			(10.6)			(3.1)			(2.3)			(2.6)				(0.2)
Net assets acquired						162.9			33.7			12.3			6.1			5.2				4.9
Uncollectable receivable amount				0.4																0.4
Goodwill, deductible for tax purposes	$ 25.4

[1] Represents fair value of trade accounts receivable, which for each of the Air Serv and BEST acquisitions includes a $0.4 million adjustment to gross contractual amounts that are expected to be uncollectible. The fair values of trade accounts receivable acquired in the HHA, Alpha, Calvert-Jones, and Blackjack acquisitions approximate their respective contractual amounts.

[2] The following table summarizes the weighted-average useful lives in years of the acquired other intangible assets, consisting primarily of customer contracts and relationships, for each respective acquisition:Air Serv HHA Alpha Calvert-Jones Blackjack BEST14 13 9 12 11 9

[3] The total amount of goodwill that is deductible for tax purposes is $25.4 million.