Litigation and Regulatory Matters - Additional Information (Detail) (USD $)	12 Months Ended	1 Months Ended	3 Months Ended		93 Months Ended	11 Months Ended	3 Months Ended		12 Months Ended	1 Months Ended	12 Months Ended		3 Months Ended
	Feb. 28, 2013 servicers	Dec. 31, 2011 Securities Litigation [Member] claim	Mar. 31, 2013 Securities Litigation [Member]	Aug. 31, 2002 Securities Litigation [Member] States	Mar. 31, 2013 Cards Litigation [Member] class_action	May 31, 2011 Debt Cancellation Litigation [Member] class_action	Mar. 31, 2013 Foreclosure Litigation [Member] servicers State	Dec. 31, 2012 Foreclosure Litigation [Member]	Dec. 31, 2012 Foreclosure Litigation [Member]	Apr. 30, 2012 Hawaii Attorney General [Member] Debt Cancellation Litigation [Member] company	Feb. 28, 2013 HSBC Bank USA [Member] Foreclosure Litigation [Member]	Dec. 31, 2012 HSBC Bank USA [Member] Foreclosure Litigation [Member]	Mar. 31, 2013 Minimum [Member] Securities Litigation [Member]	Mar. 31, 2013 Maximum [Member] Securities Litigation [Member]	Mar. 31, 2013 TCPA [Member] Telephone Consumer Protection Act 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													1,450,000,000	2,170,000,000
Claims still open to special court			720,000,000
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			3,500,000,000
Statutory damages for each violation															500
Statutory damages for each willful violation															1,500
Class actions filed					4	8
Number of credit card companies have lawsuits	12									7
Cash payments mortgage servicers would pay in excess	9,300,000,000
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 states in settlement with U.S. mortgage servicers							49
Number of U.S. mortgage servicers							5
Accrual								$ 157,000,000