Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended										1 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Sep. 13, 2011	Aug. 19, 2011	Dec. 31, 2010	Feb. 28, 2008	Sep. 30, 2011 Other Auction Rate Securities Claims	Dec. 31, 2010 Other Auction Rate Securities Claims	May 31, 2009 Overdrafts Fee Cases legalmatter	May 31, 2009 Trust Preferred Securities legalmatter	Nov. 30, 2009 Collateralized Debt Obligations	Sep. 30, 2011 Lower Limit	Sep. 30, 2011 Upper Limit
Aggregate range of reasonably possible losses on legal matters in excess of the accrued liability														$ 160	$ 260
Reserved for the remaining probable loss that could be reasonably estimated									7	24
Contingent Receipt, Judgement Award for Damages						34
Contingent Payments					5
Contingent Receipt, Prejudgement Interest Award						6
Accrued fines for settlement with FINRA	5		5
Total amount of ARS the Company has purchased	617		617
Cumulative losses on ARS	112		112
Fair value of ARS purchased pursuant to the pending settlement, trading securities	43		43				147
Fair value of ARS purchased pursuant to the pending settlement, available for sale securities	104		104				128
Total gain (loss) relating to the ARS agreements recognized	1	2	34	10
Auction rate securities par amount at the time of the collapse of the auction rate market								152
Auction rate securities accrued and settled			14
Number of putative class actions											2	3
Amount sold of an asset that is now related to a loss contingency												$ 690
Complaint allegations													the security has lost over $5 million in value