Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2021	Jul. 31, 2020
Income Statement [Abstract]
Revenues	$ 1,543.1	$ 1,394.1	$ 4,533.0	$ 4,503.0
Operating expenses	1,288.1	1,174.9	3,812.0	3,914.8
Selling, general and administrative expenses	253.8	113.7	538.3	350.8
Restructuring and related expenses	0.0	0.0	0.0	5.0
Amortization of intangible assets	10.6	11.8	32.1	37.0
Impairment loss of goodwill and other intangibles	0.0	0.0	0.0	172.8
Operating (loss) profit	(9.4)	93.6	150.6	22.8
Income from unconsolidated affiliates	0.5	0.2	1.4	2.0
Interest expense	(6.3)	(13.8)	(22.6)	(34.5)
(Loss) income from continuing operations before income taxes	(15.2)	80.0	129.4	(9.7)
Income tax benefit (provision)	1.5	(24.0)	(37.4)	(43.2)
(Loss) income from continuing operations	(13.7)	56.0	92.0	(52.9)
Income from discontinued operations, net of taxes	0.0	0.0	0.0	0.1
Net (loss) income	(13.7)	56.0	92.0	(52.8)
Other comprehensive (loss) income
Interest rate swaps	0.7	0.7	3.5	(9.2)
Foreign currency translation and other	0.1	4.3	5.3	0.5
Income tax (provision) benefit	(0.2)	(0.2)	(1.0)	2.5
Comprehensive (loss) income	$ (13.1)	$ 60.8	$ 99.9	$ (59.0)
Net (loss) income per common share — Basic
(Loss) income from continuing operations (in USD per share)	$ (0.20)	$ 0.84	$ 1.37	$ (0.79)
Income from discontinued operations (in USD per share)	0	0	0	0
Net (loss) income (in USD per share)	(0.20)	0.84	1.37	(0.79)
Net (loss) income per common share — Diluted
(Loss) income from continuing operations (in USD per share)	(0.20)	0.83	1.36	(0.79)
Income from discontinued operations (in USD per share)	0	0	0	0
Net (loss) income (in USD per share)	$ (0.20)	$ 0.83	$ 1.36	$ (0.79)
Weighted-average common and common equivalent shares outstanding
Basic (in shares)	67.5	66.9	67.3	66.9
Diluted (in shares)	67.5	67.2	67.8	66.9