Investment Securities (Details 3) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013
Available For Sale Securities Debt Maturities Amortized Cost [Abstract]
Due within 1 year	$ 478
Due after 1 year but within 5 years	509
Due after 5 years but within 10 years	175
Due after 10 years	4,109
Total	5,271
Estimated Fair Value
Estimated Fair Value, Due within 1 year	479
Estimated Fair Value, Due after 1 year but within 5 years	519
Estimated Fair Value, Due after 5 years but within 10 years	188
Estimated Fair Value, Due after 10 years	4,305
Total	$ 5,491

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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