Restructuring and Related Costs - Restructuring and Related Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2015
Restructuring Reserve [Roll Forward]
Balance, beginning	$ 8.6	$ 8.4	$ 8.0	$ 6.6	$ 0.0
Costs recognized	11.2	25.7	20.9	29.0	12.7
Costs recognized			22.6
Payments	(12.9)	(24.7)	(23.0)	(25.2)	(3.3)
Non-cash charges		(0.7)		(2.5)	(2.8)
Non-cash items			(0.9)
Balance, ending	7.0	8.6	8.4	8.0	6.6
External Support Fees
Restructuring Reserve [Roll Forward]
Balance, beginning	0.0	2.5	1.2	2.1	0.0
Costs recognized	1.5	4.0		11.3	4.6
Costs recognized			12.1
Payments	(1.0)	(6.5)	(10.8)	(12.2)	(2.5)
Non-cash charges		0.0		0.0	0.0
Non-cash items			0.0
Balance, ending	0.5	0.0	2.5	1.2	2.1
Employee Severance
Restructuring Reserve [Roll Forward]
Balance, beginning	3.8	2.7	3.8	4.3	0.0
Costs recognized	4.6	11.0		8.6	4.7
Costs recognized			2.2
Payments	(5.3)	(9.9)	(3.3)	(9.1)	(0.4)
Non-cash charges		0.0		0.0	0.0
Non-cash items			0.0
Balance, ending	3.0	3.8	2.7	3.8	4.3
Other Project Fees
Restructuring Reserve [Roll Forward]
Balance, beginning	1.8	0.4	0.5	0.2	0.0
Costs recognized	4.5	8.2		3.9	0.8
Costs recognized			5.7
Payments	(5.6)	(6.7)	(5.8)	(3.6)	(0.4)
Non-cash charges		0.0		0.0	(0.2)
Non-cash items			0.0
Balance, ending	0.7	1.8	0.4	0.5	0.2
Lease Exit
Restructuring Reserve [Roll Forward]
Balance, beginning	3.1	2.8	2.5	0.0	0.0
Costs recognized	0.7	2.0		3.2	0.0
Costs recognized			2.6
Payments	(1.1)	(1.5)	(3.1)	(0.3)	0.0
Non-cash charges		(0.2)		(0.4)	0.0
Non-cash items			(0.9)
Balance, ending	2.7	3.1	2.8	2.5	0.0
Asset Impairment
Restructuring Reserve [Roll Forward]
Balance, beginning	0.0	0.0	0.0	0.0	0.0
Costs recognized	0.0	0.6		2.1	2.6
Costs recognized			0.0
Payments	0.0	0.0	0.0	0.0	0.0
Non-cash charges		(0.6)		(2.1)	(2.6)
Non-cash items			0.0
Balance, ending	$ 0.0	$ 0.0	$ 0.0	$ 0.0	$ 0.0