Net Income Per Common Share - Basic and Diluted Net Income Per Common Share Calculations (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended										12 Months Ended
	Oct. 31, 2017		Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016		Apr. 30, 2016	Jan. 31, 2016	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2015
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income from continuing operations	$ (2.5)		$ 32.9	$ 31.6	$ 16.1	$ 9.0	$ 32.9		$ 6.8	$ 13.6	$ 78.1	$ 62.3	$ 54.1
(Loss) income from discontinued operations, net of taxes	(1.1)		0.0	(0.4)	(72.9)	(1.2)	(1.8)		(2.4)	0.4	(74.3)	(5.1)	22.2
Net income	$ (3.6)	[1]	$ 32.9	$ 31.3	$ (56.8)	$ 7.8	$ 31.1	[2]	$ 4.4	$ 14.0	$ 3.8	$ 57.2	$ 76.3
Weighted-average common and common equivalent shares outstanding—Basic (in shares)											57.7	56.3	56.7
Effect of dilutive securities
Weighted-average common and common equivalent shares outstanding—Diluted (in shares)											58.3	56.9	57.4
Net income per common share — Basic
Income from continuing operations (usd per share)	$ (0.04)		$ 0.59	$ 0.56	$ 0.29	$ 0.16	$ 0.58		$ 0.12	$ 0.24	$ 1.35	$ 1.11	$ 0.95
(Loss) income from discontinued operations (usd per share)	(0.02)		0.00	(0.01)	(1.30)	(0.02)	(0.03)		(0.04)	0.01	(1.29)	(0.09)	0.40
Net income (usd per share)	(0.06)		0.59	0.56	(1.01)	0.14	0.55		0.08	0.25	0.07	1.02	1.35
Net income per common share — Diluted
Income from continuing operations (usd per share)	(0.04)		0.58	0.56	0.28	0.16	0.58		0.12	0.24	1.34	1.09	0.94
(Loss) income from discontinued operations (usd per share)	(0.02)		0.00	(0.01)	(1.28)	(0.02)	(0.03)		(0.04)	0.00	(1.27)	(0.09)	0.39
Net income (usd per share)	$ (0.06)	[1]	$ 0.58	$ 0.55	$ (1.00)	$ 0.14	$ 0.55	[2]	$ 0.08	$ 0.24	$ 0.07	$ 1.01	$ 1.33
RSUs
Effect of dilutive securities
Effect of dilutive securities (in shares)											0.3	0.3	0.3
Stock options
Effect of dilutive securities
Effect of dilutive securities (in shares)											0.2	0.2	0.3
Performance shares
Effect of dilutive securities
Effect of dilutive securities (in shares)											0.1	0.1	0.1

[1] Includes transaction expenses of $22.0 million, or $0.38 per diluted share, related to the GCA acquisition

[2] Includes a tax benefit of $19.0 million, or $0.33 per diluted share, related to expiring statutes of limitations.