Net Income Per Common Share - Calculations of Basic and Diluted Net Income Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2016	Apr. 30, 2015
Schedule of Earnings Per Share, Basic and Diluted, by Common Class
Income from continuing operations	$ 6.8	$ 16.0	$ 20.4	$ 30.3
Net (loss) income from discontinued operations	(2.4)	2.3	(2.0)	5.7
Net income	$ 4.4	$ 18.3	$ 18.4	$ 36.0
Weighted-average common and common equivalent shares outstanding-Basic (in shares)	56.4	56.8	56.5	56.6
Effect of dilutive securities:
Weighted-average common and common equivalent shares outstanding-Diluted (in shares)	56.9	57.6	57.0	57.4
Net income per common share — Basic:
Income from continuing operations (in dollars per share)	$ 0.12	$ 0.28	$ 0.36	$ 0.54
(Loss) income from discontinued operations (in dollars per share)	(0.04)	0.04	(0.04)	0.10
Net income (in dollars per share)	0.08	0.32	0.32	0.64
Net income per common share — Diluted:
Income from continuing operations (in dollars per share)	0.12	0.28	0.36	0.53
(Loss) income from discontinued operations (in dollars per share)	(0.04)	0.04	(0.04)	0.10
Net income (in dollars per share)	$ 0.08	$ 0.32	$ 0.32	$ 0.63
Restricted stock units
Effect of dilutive securities:
Effect of dilutive securities (in shares)	0.2	0.4	0.2	0.3
Stock options
Effect of dilutive securities:
Effect of dilutive securities (in shares)	0.2	0.3	0.2	0.3
Performance shares
Effect of dilutive securities:
Effect of dilutive securities (in shares)	0.1	0.1	0.1	0.2