Income Taxes - Components of Income Tax Benefit (Expense) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Oct. 31, 2014	Apr. 30, 2014	Oct. 31, 2015	Oct. 31, 2014	Oct. 31, 2013
Income Tax Disclosure [Abstract]
Current Federal Tax Expense (Benefit)			$ (2)	$ 0	$ 4
Current State and Local Tax Expense (Benefit)			(1)	7	(10)
Current Foreign Tax Expense (Benefit)			(64)	(48)	(58)
Current Income Tax Expense (Benefit)			(67)	(41)	(64)
Deferred Federal Income Tax Expense (Benefit)			2	13	219
Deferred State and Local Income Tax Expense (Benefit)			0	0	2
Deferred Foreign Income Tax Expense (Benefit)			14	2	14
Deferred Income Tax Expense (Benefit)			16	15	235
Income Tax Expense (Benefit)			(51)	(26)	171
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ (16)	$ 29	$ 41	$ 234	$ 350