Income Taxes (Narrative) (Details) £ in Millions, $ in Millions		3 Months Ended			12 Months Ended
	Dec. 20, 2017 GBP (£)	Jan. 31, 2018 GBP (£)	Jan. 31, 2018 USD ($)	Jan. 31, 2017	Oct. 31, 2018	Oct. 31, 2017 USD ($)
Operating Loss Carryforwards [Line Items]
Repatriation tax			$ 177.9
Provisional tax expense			13.2
Current state and local tax expense (benefit)			8.1
Withholding taxes relating to the unremitted foreign earnings			$ 2.8
Effective tax rate (ETR)		263.70%	263.70%	5.40%
Effective tax rate increase			$ 202.0
Unrecognized tax benefits			59.9			$ 61.9
Unrecognized tax benefits related to tax positions			$ 6.1
UNITED KINGDOM
Operating Loss Carryforwards [Line Items]
Diverted profit tax | £	£ 31.0	£ 31.0
Scenario, Forecast
Operating Loss Carryforwards [Line Items]
Blended tax rate					23.34%