Revenue - Consolidated Statements of Operations (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Jan. 31, 2019	Jan. 31, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	$ 1,607.9	$ 1,588.3
Operating expenses	1,446.0	1,429.3
Selling, general and administrative expenses	112.7	109.0
Income tax (provision) benefit	(4.7)	22.2
Net income	$ 13.0	$ 27.8
Net income per common share — Basic (in usd per share)	$ 0.20	$ 0.42
Net income per common share — Diluted (in usd per share)	$ 0.19	$ 0.42
Under Historical Guidance
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	$ 1,617.9
Operating expenses	1,457.3
Selling, general and administrative expenses	113.6
Income tax (provision) benefit	(4.2)
Net income	$ 11.3
Net income per common share — Basic (in usd per share)	$ 0.17
Net income per common share — Diluted (in usd per share)	$ 0.17
Effect of Adoption | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	$ (10.0)
Operating expenses	(11.3)
Selling, general and administrative expenses	(0.9)
Income tax (provision) benefit	(0.6)
Net income	$ 1.7
Net income per common share — Basic (in usd per share)	$ 0.03
Net income per common share — Diluted (in usd per share)	$ 0.03