Fair Value and Investment Securities Maturity Distribution Based on Contractual Terms of Investment Securities (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Available-For-Sale Amortized Cost
Due within 1 year	$ 1,418
Due after 1 year through 5 years	1,254
Due after 5 years through 10 years	59
Due after 10 years	35
No contractual maturity	209
Total	2,975
Available-For-Sale Fair Value
Due within 1 year	1,418
Due after 1 year through 5 years	1,263
Due after 5 years through 10 years	60
Due after 10 years	32
No contractual maturity	210
Total	$ 2,983

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