FAIR VALUE MEASUREMENT (Details 6) (USD $)	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010
Assets.
Investments	$ 279,424,000,000	$ 274,040,000,000
Federal funds sold and securities borrowed or purchased under agreements to resell	172,435,000,000	142,862,000,000
Loans	4,744,000,000	5,265,000,000	4,351,000,000
Other financial assets	9,413,000,000	13,360,000,000
Liabilities;
Deposits	906,012,000,000	865,936,000,000
Federal funds purchased and securities loaned or sold under agreements to repurchase	137,571,000,000	112,770,000,000
Long-term debt	26,700,000,000	24,172,000,000
Other financial liabilities	3,139,000,000	3,742,000,000
Allowance for loan losses	29,020,000,000	30,115,000,000	36,568,000,000	40,655,000,000
Lease finance receivables	2,600,000,000	2,500,000,000
Consumer
Assets.
Loans	1,314,000,000	1,326,000,000
Corporate
Assets.
Loans	3,430,000,000	3,939,000,000
Carrying value
Assets.
Investments	17,900,000,000	19,400,000,000
Federal funds sold and securities borrowed or purchased under agreements to resell	116,600,000,000	133,000,000,000
Other financial assets	282,200,000,000	245,700,000,000
Liabilities;
Deposits	904,700,000,000	864,600,000,000
Federal funds purchased and securities loaned or sold under agreements to repurchase	88,400,000,000	85,600,000,000
Long-term debt	284,400,000,000	299,300,000,000
Other financial liabilities	143,300,000,000	141,100,000,000
Carrying value | Loans, excluding lease finance receivables
Assets.
Loans	611,700,000,000	609,300,000,000
Fair value
Liabilities;
Deposits	903,900,000,000	864,500,000,000
Fair value measurements additional disclosures
Estimated fair values of corporate unfunded lending commitments	7,100,000,000	4,700,000,000
Fair value | Loans, excluding lease finance receivables
Assets.
Loans	599,400,000,000	598,700,000,000
Financial instruments not carried at Fair Value | Loans, excluding lease finance receivables
Fair value measurements additional disclosures
Aggregate carrying value in excess of (less than) fair value	(12,300,000,000)	(10,600,000,000)
Financial instruments not carried at Fair Value | Consumer
Fair value measurements additional disclosures
Aggregate carrying value in excess of (less than) fair value	8,400,000,000
Financial instruments not carried at Fair Value | Corporate
Fair value measurements additional disclosures
Aggregate carrying value in excess of (less than) fair value	3,900,000,000
Financial instruments not carried at Fair Value | Level 1
Assets.
Other financial assets	9,900,000,000
Financial instruments not carried at Fair Value | Level 2
Assets.
Investments	15,500,000,000
Federal funds sold and securities borrowed or purchased under agreements to resell	109,000,000,000
Other financial assets	240,800,000,000
Liabilities;
Deposits	837,200,000,000
Federal funds purchased and securities loaned or sold under agreements to repurchase	87,000,000,000
Long-term debt	236,200,000,000
Other financial liabilities	92,100,000,000
Financial instruments not carried at Fair Value | Level 2 | Loans, excluding lease finance receivables
Assets.
Loans	4,700,000,000
Financial instruments not carried at Fair Value | Level 3
Assets.
Investments	1,900,000,000
Federal funds sold and securities borrowed or purchased under agreements to resell	7,600,000,000
Other financial assets	31,300,000,000
Liabilities;
Deposits	66,700,000,000
Federal funds purchased and securities loaned or sold under agreements to repurchase	1,400,000,000
Long-term debt	48,200,000,000
Other financial liabilities	51,200,000,000
Financial instruments not carried at Fair Value | Level 3 | Loans, excluding lease finance receivables
Assets.
Loans	$ 594,700,000,000