Schedule of Contractual Maturities of Debt Securities Available for Sale (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Investments Classified by Contractual Maturity Date [Line Items]
Due within one year, Amortized Cost	$ 473
Due after one year through five years, Amortized Cost	1,833
Due after five years through ten years, Amortized Cost	2,768
Due after ten years, Amortized Cost	1,850
Mortgage and asset-backed securities, Amortized Cost	2,060
Total debt securities, Amortized Cost	8,984	9,119
Due within one year, Fair Value	478
Due after one year through five years, Fair Value	1,899
Due after five years through ten years, Fair Value	2,900
Due after ten years, Fair Value	1,955
Mortgage and asset-backed securities, Fair Value	2,094
Total debt securities, Fair Value	$ 9,326	$ 9,847

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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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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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