Income Taxes - Narrative (Details) $ in Millions	3 Months Ended	12 Months Ended
	Oct. 31, 2019 USD ($) state	Oct. 31, 2019 USD ($) state	Oct. 31, 2018 USD ($)	Oct. 31, 2017 USD ($)
Income Taxes [Line Items]
U.S. statutory rate		21.00%	23.30%	35.00%
Net discrete tax benefit from remeasurement of deferred taxes at new rate due to Tax Act			$ 29.6
Remeasurement of one-time transition tax on deemed repatriation of indefinitely reinvested earnings	$ (1.8)	$ (2.7)	$ (4.5)
Effective tax rate (percent)		20.40%	(9.40%)	10.10%
Income tax provision		$ (32.7)	$ 8.2	$ (8.8)
State true-ups		(1.7)
Federal true-ups		(1.6)
Work opportunity tax credit, adjustment		1.3	1.0
Tax benefit related to lapse of statute of limitations		(1.3)	(5.8)
Income tax benefit related to vesting of share-based compensation awards		(1.1)	(3.4)
Benefit resulting from research and development credits		(0.9)
Tax benefits, implementation of tax act			23.2
Income tax benefit related to deduction for energy efficient government buildings			(2.8)
Tax credits	7.6	7.6
Unrecognized tax benefits that would impact effective tax rate	35.3	35.3	35.8	50.5
Maximum decrease in unrecognized tax benefits that is reasonably possible	4.7	4.7
Uncertain tax positions, interest and penalties accrued	$ 1.2	1.2	1.0
Unrecognized tax benefits, interest and penalties expense		$ 0.2
Unrecognized tax benefits, interest and penalties benefit			$ (1.0)	$ (0.5)
Number of states in which entity operates | state	50	50
State and Local Jurisdiction
Income Taxes [Line Items]
Operating loss carryforwards	$ 144.8	$ 144.8