Credit Facility - Interest Rate Swaps Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019	Oct. 31, 2019
Line of Credit Facility [Line Items]
Interest expense	$ 13.8	$ 12.9	$ 34.5	$ 39.2
Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net	(4.1)		(4.1)
Tax to be reclassified during next 12 months	(1.4)		(1.4)
Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest
Line of Credit Facility [Line Items]
Net gains from cash flow hedges recorded in accumulated other comprehensive loss, net of tax			(4.5)		$ 2.2
Tax related to amounts in accumulated other comprehensive loss			(1.3)		$ 1.2
Interest expense	(1.2)	1.0	(3.6)	3.1
Interest expense, tax	$ 0.5	$ 0.4	$ 1.4	$ 1.2