Net Income (Loss) Per Common Share - Calculations of Basic and Diluted Net Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2021	Apr. 30, 2020
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income (loss) from continuing operations	$ 31.1	$ (136.8)	$ 105.7	$ (108.9)
Income from discontinued operations, net of taxes	0.0	0.0	0.0	0.1
Net income (loss)	$ 31.1	$ (136.8)	$ 105.7	$ (108.8)
Weighted-average common and common equivalent shares outstanding — Basic (in shares)	67.3	66.9	67.2	66.9
Effect of dilutive securities
Weighted-average common and common equivalent shares outstanding — Diluted (in shares)	67.8	66.9	67.7	66.9
Net income (loss) per common share — Basic
Income (loss) from continuing operations (in USD per share)	$ 0.46	$ (2.05)	$ 1.57	$ (1.63)
Income from discontinued operations (in USD per share)	0	0	0	0
Net income (loss) (in USD per share)	0.46	(2.05)	1.57	(1.63)
Net income (loss) per common share — Diluted
Income (loss) from continuing operations (in USD per share)	0.46	(2.05)	1.56	(1.63)
Income from discontinued operations (in USD per share)	0	0	0	0
Net income (loss) (in USD per share)	$ 0.46	$ (2.05)	$ 1.56	$ (1.63)
Restricted stock units
Effect of dilutive securities
Effect of dilutive securities (in shares)	0.4	0.0	0.3	0.0
Performance shares
Effect of dilutive securities
Effect of dilutive securities (in shares)	0.0	0.0	0.1	0.0