Receivables - Nonaccrual Receivables (Detail) (USD $)	Mar. 31, 2013		Dec. 31, 2012
Nonaccrual receivables:
Total nonaccrual receivables	$ 5,226,000,000		$ 5,193,000,000
Real estate secured [Member]
Nonaccrual receivables:
Total nonaccrual receivables	2,894,000,000	[1]	3,032,000,000	[1]
Nonaccrual receivables held for sale [Member]
Nonaccrual receivables:
Total nonaccrual receivables	2,332,000,000		2,161,000,000
Real estate secured [Member]
Nonaccrual receivables:
Nonaccrual Real Estate Secured Receivables Carried At Lower Amortized Cost Or Fair Value	$ 1,900,000,000		$ 1,700,000,000

[1] At March 31, 2013 and December 31, 2012, nonaccrual real estate secured receivables held for investment include $1.9 billion and $1.7 billion, respectively, of receivables that are carried at the lower of amortized cost or fair value of the collateral less cost to sell.