Investment Securities (Details 3) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012
Available For Sale Securities Debt Maturities Amortized Cost [Abstract]
Due within 1 year	$ 507
Due after 1 year through 5 years	344
Due after 5 years through 10 years	166
Due after 10 years	4,468
Total	5,485
Estimated Fair Value
Estimated Fair Value, Due within 1 year	509
Estimated Fair Value, Due after 1 year through 5 years	353
Estimated Fair Value, Due after 5 years through 10 years	179
Estimated Fair Value, Due after 10 years	4,684
Total	$ 5,725

Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the sixth fiscal year through the tenth fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the second fiscal year through the fifth fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing after the tenth fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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