Loans and Loans Held for Sale - Summary of Changes in Loans Held for Sale (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Loans [Line Items]
Balance at beginning of the period	$ 728	$ 467
New originations	5,209	3,982
Transfers from held to maturity, net	77	90
Loan sales	(5,391)	(3,721)
Loan draws (payments), net	(20)	(60)
Transfers to OREO / valuation adjustments	(4)	(30)
Balance at end of period	$ 599	$ 728

The aggregate carrying amount of loans receivable that will be sold to other entities. Includes mortgage and all other loans (collectively, loans) not classified as held for investment. Such loans are stated at the lower of cost or market, or elected fair value. Mortgage loans exclude mortgage-backed securities which are considered a debt security (other loan).

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+ Details