Litigation and Regulatory Matters - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended		12 Months Ended			1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2011 Securities Litigation [Member] claim	Dec. 31, 2012 Securities Litigation [Member]	Aug. 31, 2002 Securities Litigation [Member] States	Dec. 31, 2012 Telephone Consumer Protection Act Litigation [Member] class_action	Dec. 31, 2012 Cards Litigation [Member] class_action	Dec. 31, 2012 Debt Cancellation Litigation [Member] class_action	Oct. 31, 2012 Foreclosure Litigation [Member] county	Dec. 31, 2011 Foreclosure Litigation [Member]	Dec. 31, 2012 Foreclosure Litigation [Member] servicers State	Dec. 31, 2012 Hawaii Attorney General [Member] Debt Cancellation Litigation [Member] company	Dec. 31, 2012 TCPA [Member] Telephone Consumer Protection Act Litigation [Member]	Dec. 31, 2012 Minimum [Member] Securities Litigation [Member]	Dec. 31, 2012 Minimum [Member] Special Master [Member] Securities Litigation [Member]	Dec. 31, 2012 Maximum [Member] Securities Litigation [Member]	Dec. 31, 2012 HSBC Bank USA [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												1,370,000,000	800,000,000	2,170,000,000
Number of days to appeal verdict to Seventh Circuit Court of Appeals		30 days
Possible amount of damages		2,700,000,000
Possible future expenses related to amount of damages		2,700,000,000
Class actions filed				5	4	8
Statutory damages for each violation											500
Statutory damages for each willful violation											1,500
Number of credit card companies have lawsuits										7
Cash payment into a fund hat will be used to make payments to borrowers															96,000,000
Recorded expenses in period									85,000,000						104,000,000
Number of mortgage servicers									12
Cash payments mortgage serviers would pay in excess									9,300,000,000
Number of states in settlement with U.S. mortgage servicers									49
Number of U.S. mortgage servicers									5
Accrual								$ 157,000,000
Number of counties filings a lawsuit							3