Litigation and Regulatory Matters - Additional Information (Detail) (USD $)	9 Months Ended	12 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended
	Sep. 30, 2012 Securities Litigation [Member]	Dec. 31, 2011 Securities Litigation [Member] Claim	Aug. 31, 2002 Securities Litigation [Member] States	Sep. 30, 2012 Cards Litigation [Member] ClassAction	Sep. 30, 2012 Debt Cancellation Litigation [Member] ClassAction	Dec. 31, 2011 Foreclosure Litigation [Member]	Sep. 30, 2012 Foreclosure Litigation [Member] Servicers State	Sep. 30, 2012 Hawaii Attorney General [Member] Debt Cancellation Litigation [Member] Company	Sep. 30, 2012 Mississippi Attorney General [Member] Debt Cancellation Litigation [Member] Company	Sep. 30, 2012 Plaintiffs [Member]	Sep. 30, 2012 Defendants [Member]	Sep. 30, 2012 Minimum [Member] Securities Litigation [Member]	Sep. 30, 2012 Minimum [Member] Foreclosure Litigation [Member]	Sep. 30, 2012 Maximum [Member] Securities Litigation [Member]	Sep. 30, 2012 Maximum [Member] Foreclosure Litigation [Member]
Loss Contingencies [Line Items]
Number of states in 2002 settlement			46
Estimated damage												$ 2,400,000,000		$ 3,200,000,000
Total claims of loss		45,921
Aggregate amount of claims		2,230,000,000
Litigation judgment claims										1,500,000,000	275,000,000
Number of days to appeal verdict to Seventh Circuit Court of Appeals	30 days
Possible amount of damages	3,500,000,000
Possible future expenses related to amount of damages	3,000,000,000
Class actions filed				4	8
Number of credit card companies have lawsuits								7	6
Lump sum payment due as remediation available to borrower, range													500		125,000
Number of states in settlement with U.S. mortgage servicers							49
Number of U.S. mortgage servicers							5
Accrual						$ 157,000,000