Income Taxes - Components of Income Tax Benefit (Expense) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Oct. 31, 2014	Apr. 30, 2014	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2012
Income Tax Disclosure [Abstract]
Current Federal Tax Expense (Benefit)			$ 0	$ 4	$ (2)
Current State and Local Tax Expense (Benefit)			7	(10)	(11)
Current Foreign Tax Expense (Benefit)			(48)	(58)	4
Current Income Tax Expense (Benefit)			(41)	(64)	(9)
Deferred Federal Income Tax Expense (Benefit)			13	219	(1,841)
Deferred State and Local Income Tax Expense (Benefit)			0	2	(137)
Deferred Foreign Income Tax Expense (Benefit)			2	14	207
Deferred Income Tax Expense (Benefit)			15	235	(1,771)
Income Tax Expense (Benefit)			(26)	171	(1,780)
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ (16)	$ 29	$ 234	$ 350	$ 2,200