Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Jul. 31, 2016	Jan. 31, 2016	Jul. 31, 2015	Jul. 31, 2016	Jul. 31, 2015
Operating Loss Carryforwards [Line Items]
Income Taxes Percent Likelihood Of Being Realized Upon Settlement	50.00%			50.00%
Income Tax Expense (Benefit)	$ 14		$ 12	$ 25	$ 37
Unrecognized Tax Benefits	42			42
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	1			$ 1
Other Comprehensive Income (Loss) [Member]
Operating Loss Carryforwards [Line Items]
Income Tax Expense (Benefit)	$ (12)
Alternative Minimum Tax [Member]
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount		$ 13