Credit Loss Reserves - Summarizes Changes in Credit Loss Reserves by Product/Class and Related Receivable Balance by Product (Parenthetical) (Detail) (USD $)	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Financing Receivable, Allowance for Credit Losses [Line Items]
Excludes TDR Loans that are carried at the lower of amortized cost or fair value	$ 1,000,000,000	$ 2,200,000,000
Excludes Credit loss reserves for TDR Loans that are carried at the lower of amortized cost or fair value	61,000,000	139,000,000
Provision for credit losses related to the lower of amortized cost or fair value attributable to credit for personal non-credit card receivables	$ 112,000,000