Investment Securities (Contractual maturities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Investment [Line Items]
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis	$ 2,366
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis	3,300
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis	4,984
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis	18,024
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value	2,374
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value	3,502
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value	5,156
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value	$ 19,901

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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 fair value maturing in the sixth fiscal year through the tenth fiscal year following the latest fiscal year.

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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 fair value maturing in the second fiscal year through the fifth fiscal year following the latest fiscal year.

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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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Amount of available-for-sale debt securities at fair value maturing after the tenth fiscal year following the latest fiscal year.

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Amount of available-for-sale debt securities at fair value maturing in the next fiscal year following the latest fiscal year.

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