Selected Quarterly Financial Data (Unaudited) - Financial Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Oct. 31, 2020	Jul. 31, 2020	Apr. 30, 2020	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 1,484.6	$ 1,394.1	$ 1,496.0	$ 1,612.9	$ 1,648.0	$ 1,647.9	$ 1,594.7	$ 1,607.9	$ 5,987.6	$ 6,498.6	$ 6,442.2
Gross profit	242.4	219.2	189.9	179.2	194.7	193.9	180.5	162.0
Income (loss) from continuing operations	53.1	56.0	(136.8)	27.9	48.1	36.5	29.9	13.0	0.2	127.5	95.9
Income (loss) from discontinued operations, net of taxes	0.0	0.0	0.0	0.1	(0.1)	0.2	(0.2)	(0.1)	0.1	(0.1)	1.8
Net income (loss)	$ 53.1	$ 56.0	$ (136.8)	$ 28.0	$ 47.9	$ 36.8	$ 29.7	$ 13.0	$ 0.3	$ 127.4	$ 97.8
Net income (loss) per common share — Basic
Income (loss) from continuing operations (usd per share)	$ 0.79	$ 0.84	$ (2.05)	$ 0.42	$ 0.72	$ 0.55	$ 0.45	$ 0.20	$ 0.00	$ 1.92	$ 1.45
Income from discontinued operations (usd per share)	0	0	0	0	0	0	0	0	0	0	0.03
Net income (usd per share)	0.79	0.84	(2.05)	0.42	0.72	0.55	0.45	0.20	0.00	1.91	1.48
Net income (loss) per common share — Diluted
Income (loss) from continuing operations (usd per share)	0.78	0.83	(2.05)	0.41	0.71	0.55	0.45	0.20	0.00	1.91	1.45
Income from discontinued operations (usd per share)	0	0	0	0	0	0	0	0	0	0	0.03
Net income (usd per share)	$ 0.78	$ 0.83	$ (2.05)	$ 0.42	$ 0.71	$ 0.55	$ 0.45	$ 0.19	$ 0.00	$ 1.90	$ 1.47