Leases - Lease Cost (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Apr. 30, 2020	Apr. 30, 2020
Operating lease costs:
Operating lease, cost	$ 24.6	$ 51.2
Finance lease costs:
Operating expenses(4)	1.0	2.1
Interest expense(5)	0.2	0.3
Total lease costs	25.8	53.6
Short-term lease costs	11.9	26.4
Variable lease costs	1.0	3.0
Total short-term and variable lease costs	12.9	29.4
Operating expenses(1)(2)
Operating lease costs:
Operating lease, cost	17.1	38.1
Selling, general and administrative expenses(3)
Operating lease costs:
Operating lease, cost	$ 7.5	$ 13.1