Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Income Statement [Abstract]
Revenues	$ 1,394.1	$ 1,647.9	$ 4,503.0	$ 4,850.6
Operating expenses	1,174.9	1,454.1	3,914.8	4,314.2
Selling, general and administrative expenses	113.7	119.8	350.8	340.9
Restructuring and related expenses	0.0	2.0	5.0	8.5
Amortization of intangible assets	11.8	14.9	37.0	44.9
Impairment loss	0.0	0.0	172.8	0.0
Operating profit	93.6	57.3	22.8	142.1
Income from unconsolidated affiliates	0.2	0.7	2.0	2.4
Interest expense	(13.8)	(12.9)	(34.5)	(39.2)
Income (loss) from continuing operations before income taxes	80.0	45.0	(9.7)	105.3
Income tax provision	(24.0)	(8.5)	(43.2)	(25.8)
Income (loss) from continuing operations	56.0	36.5	(52.9)	79.4
Income from discontinued operations, net of taxes	0.0	0.2	0.1	0.0
Net income (loss)	56.0	36.8	(52.8)	79.4
Other comprehensive income (loss)
Interest rate swaps	0.7	(5.7)	(9.2)	(17.9)
Foreign currency translation	4.3	(4.6)	0.5	(2.4)
Income tax (provision) benefit	(0.2)	1.6	2.5	4.9
Comprehensive income (loss)	$ 60.8	$ 28.0	$ (59.0)	$ 64.0
Net income (loss) per common share — Basic
Income (loss) from continuing operations (in usd per share)	$ 0.84	$ 0.55	$ (0.79)	$ 1.19
Income (loss) from discontinued operations (in usd per share)	0	0	0	0
Net income (loss) (in usd per share)	0.84	0.55	(0.79)	1.19
Net income (loss) per common share — Diluted
Income (loss) from continuing operations (in usd per share)	0.83	0.55	(0.79)	1.19
Income (loss) from discontinued operations (in usd per share)	0	0	0	0
Net income (loss) (in usd per share)	$ 0.83	$ 0.55	$ (0.79)	$ 1.19
Weighted-average common and common equivalent shares outstanding
Basic (in shares)	66.9	66.6	66.9	66.5
Diluted (in shares)	67.2	67.0	66.9	66.8