Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2017	Apr. 30, 2016
Income Statement [Abstract]
Revenues	$ 1,310.5	$ 1,257.1	$ 2,637.2	$ 2,525.5
Operating expenses	1,164.6	1,127.5	2,359.7	2,268.9
Selling, general and administrative expenses	100.7	102.4	198.0	202.2
Restructuring and related expenses	5.8	8.8	10.8	16.0
Amortization of intangible assets	5.8	6.6	11.3	13.0
Impairment recovery	(17.4)	0.0	(17.4)	0.0
Operating profit	51.0	11.8	74.8	25.4
Income from unconsolidated affiliates, net	0.9	0.9	2.3	3.3
Interest expense	(3.0)	(2.4)	(6.3)	(5.1)
Income from continuing operations before income taxes	48.9	10.3	70.9	23.6
Income tax provision	(17.3)	(3.5)	(23.2)	(3.2)
Income from continuing operations	31.6	6.8	47.7	20.4
Net loss from discontinued operations	(0.4)	(2.4)	(73.2)	(2.0)
Net income (loss)	31.3	4.4	(25.5)	18.4
Other comprehensive income (loss)
Foreign currency translation	3.0	4.1	6.3	(4.4)
Other	0.0	0.1	1.6	0.2
Comprehensive income (loss)	$ 34.3	$ 8.6	$ (17.6)	$ 14.2
Net income (loss) per common share — Basic
Income from continuing operations (in usd per share)	$ 0.56	$ 0.12	$ 0.85	$ 0.36
Loss from discontinued operations (in usd per share)	(0.01)	(0.04)	(1.31)	(0.04)
Net income (loss) (in usd per share)	0.56	0.08	(0.46)	0.32
Net income (loss) per common share — Diluted
Income from continuing operations (in usd per share)	0.56	0.12	0.84	0.36
Loss from discontinued operations (in usd per share)	(0.01)	(0.04)	(1.29)	(0.04)
Net income (loss) (in usd per share)	$ 0.55	$ 0.08	$ (0.45)	$ 0.32
Weighted-average common and common equivalent shares outstanding
Basic (in shares)	56.0	56.4	56.0	56.5
Diluted (in shares)	56.5	56.9	56.6	57.0
Dividends declared per common share (in usd per share)	$ 0.170	$ 0.165	$ 0.34	$ 0.33