Restructuring and Related Costs - Restructuring and Related Liabilities (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2018		Apr. 30, 2017
Restructuring Reserve [Roll Forward]
Balance, beginning of period				$ 8.4
Costs recognized		$ 5.3	$ 5.8	19.6	[1]	$ 10.8
Payments				(14.9)
Non-cash charges				(1.1)
Balance, end of period		11.9		11.9
Employee Severance
Restructuring Reserve [Roll Forward]
Balance, beginning of period				2.7
Costs recognized	[1]			9.3
Payments				(6.5)
Non-cash charges				0.0
Balance, end of period		5.5		5.5
External Support Fees
Restructuring Reserve [Roll Forward]
Balance, beginning of period				2.5
Costs recognized	[1]			4.0
Payments				(6.5)
Non-cash charges				0.0
Balance, end of period		0.0		0.0
Lease Exit
Restructuring Reserve [Roll Forward]
Balance, beginning of period				2.8
Costs recognized	[1]			2.5
Payments				(0.3)
Non-cash charges				(1.1)
Balance, end of period		3.9		3.9
Other Project Fees
Restructuring Reserve [Roll Forward]
Balance, beginning of period				0.4
Costs recognized	[1]			3.8
Payments				(1.6)
Non-cash charges				0.0
Balance, end of period		$ 2.5		$ 2.5

[1] We include these costs within corporate expenses.