Income Taxes - Reconciliation between the Expected Provision for Income taxes at the US Federal Statutory Rate and the Provision for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Oct. 31, 2019
Income Tax Disclosure [Abstract]
Provision for income taxes at United States statutory tax rate	$ 103.2	$ 56.0	$ 100.3
Foreign income subject to different tax rates	(43.6)	(54.7)	(85.6)
Foreign income subject to United States tax	25.4	32.0	16.1
United States tax reform	0.0	0.0	(5.8)
Employee compensation	(9.9)	(4.4)	(7.8)
Deferred tax asset step-up	3.2	(9.0)	(6.7)
United States provision-to-return	(1.2)	7.0	4.4
Intra-group transfer to UK subsidiary	(1,987.9)	0.0	0.0
Remeasurement of deferred tax assets from UK rate change	(536.7)	0.0	0.0
Change in unrecognized tax benefits	(7.6)	(0.1)	(1.5)
Other, net	1.9	1.3	(2.7)
Provision for income taxes	$ (2,453.2)	$ 28.1	$ 10.7