Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Operating Loss Carryforwards [Line Items]
Income Taxes Percent Likelihood Of Being Realized Upon Settlement	50.00%		50.00%
Income tax expense	$ 0	$ (14)	$ (10)	$ (25)
Unrecognized Tax Benefits	49		49
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	1		1
Intraperiod Tax Allocation Rule [Member]
Operating Loss Carryforwards [Line Items]
Income tax expense	$ 35
Other Comprehensive Income (Loss) [Member]
Operating Loss Carryforwards [Line Items]
Income tax expense			$ 14