Credit Facility - Interest Rate Swaps Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2021	Jul. 31, 2020	Oct. 31, 2020
Line of Credit Facility [Line Items]
Interest expense	$ 6.3	$ 13.8	$ 22.6	$ 34.5
Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net	(0.6)		(0.6)
Tax to be reclassified during the next 12 months	(0.1)		(0.1)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Line of Credit Facility [Line Items]
Net loss from cash flow hedges recorded in accumulated other comprehensive loss, net of tax			(0.9)		$ (3.3)
Tax related to amounts in accumulated other comprehensive loss			0.1		$ (0.9)
Interest expense	(1.2)	1.2	(3.5)	(3.6)
Interest expense, tax	$ 0.4	$ 0.5	$ 1.3	$ (1.4)