Goodwill and Intangible Assets - Summary of Intangible Assets Excluding Goodwill (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Jul. 31, 2020	Oct. 31, 2019
Intangible Assets Excluding Goodwill [Line Items]
Finite-lived intangible assets, gross	$ 73.1	$ 139.8
Finite-lived intangible assets, accumulated amortization	(40.9)	(95.8)
Finite-lived intangible assets, net	32.2	44.0
Indefinite-lived trade names	110.1	115.9
Total intangible assets, gross	183.2	255.7
Total intangible assets, net	$ 142.3	$ 159.9
Customer Relationships [Member]
Intangible Assets Excluding Goodwill [Line Items]
Finite-lived intangible assets, Weighted-Average Life	8 years	8 years
Finite-lived intangible assets, gross	$ 69.8	$ 126.7
Finite-lived intangible assets, accumulated amortization	(37.9)	(84.0)
Finite-lived intangible assets, net	$ 31.9	$ 42.7
Order Backlog [Member]
Intangible Assets Excluding Goodwill [Line Items]
Finite-lived intangible assets, Weighted-Average Life		1 year
Finite-lived intangible assets, gross		$ 6.7
Finite-lived intangible assets, accumulated amortization		$ (6.7)
Non-compete Agreements [Member]
Intangible Assets Excluding Goodwill [Line Items]
Finite-lived intangible assets, Weighted-Average Life	5 years	5 years
Finite-lived intangible assets, gross	$ 2.0	$ 2.0
Finite-lived intangible assets, accumulated amortization	(1.7)	(1.3)
Finite-lived intangible assets, net	$ 0.3	$ 0.7
Trade Names [Member]
Intangible Assets Excluding Goodwill [Line Items]
Finite-lived intangible assets, Weighted-Average Life	7 years	7 years
Finite-lived intangible assets, gross	$ 1.3	$ 3.5
Finite-lived intangible assets, accumulated amortization	$ (1.3)	(3.0)
Finite-lived intangible assets, net		$ 0.5
Technology-related Intangible Assets [Member]
Intangible Assets Excluding Goodwill [Line Items]
Finite-lived intangible assets, Weighted-Average Life		7 years
Finite-lived intangible assets, gross		$ 0.9
Finite-lived intangible assets, accumulated amortization		(0.8)
Finite-lived intangible assets, net		$ 0.1