Employee Benefits - Schedule of Components of Net Periodic Defined Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2020	Apr. 30, 2019
Retirement Benefits [Abstract]
Service cost	$ 3.4	$ 2.7	$ 6.9	$ 5.4
Interest cost	1.4	1.3	2.6	2.5
Expected return on plan assets	(2.7)	(2.3)	(5.4)	(4.6)
Recognized net actuarial loss	1.0	0.4	2.0	0.8
Net periodic defined benefit plan cost	$ 3.1	$ 2.1	$ 6.1	$ 4.1