Investment Securities (Details 3) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012
Available For Sale Securities Debt Maturities Amortized Cost [Abstract]
Due within 1 year	$ 657
Due after 1 year through 5 years	394
Due after 5 years through 10 years	221
Due after 10 years	4,855
Total	6,127
Estimated Fair Value
Estimated Fair Value, Due within 1 year	663
Estimated Fair Value, Due after 1 year through 5 years	400
Estimated Fair Value, Due after 5 years through 10 years	233
Estimated Fair Value, Due after 10 years	4,960
Total	$ 6,256

This item represents debt securities, at cost, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any, which are expected to mature after five years and through ten years from the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

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