INVESTMENTS (Details 6) (USD $)	3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount;
Total carrying value	$ 10,126,000,000	$ 11,483,000,000
Held-to-maturity Securities, Debt Maturities, Fair Value;
Total fair value	9,656,000,000	10,500,000,000
Impairment charge related to total investment, pre-tax	1,181,000,000
Akbank
Held-to-maturity Securities, Debt Maturities, Fair Value;
Maximum equity method investment ownership percentage	10.00%
Equity method investment ownership percentage	20.00%
Impairment charge related to total investment, pre-tax	1,200,000,000
Impairment charge related to total investment, after-tax	763,000,000
Morgan Stanley Smith Barney joint venture (MSSB)
Held-to-maturity Securities, Debt Maturities, Fair Value;
Carrying value of equity method investment	10,000,000,000
Mortgage-backed securities
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount;
After 1 but within 5 years, carrying value	307,000,000	275,000,000
After 5 but within 10 years, carrying value	184,000,000	238,000,000
After 10 years, carrying value	6,332,000,000	6,917,000,000
Total carrying value	6,823,000,000	7,430,000,000
Held-to-maturity Securities, Debt Maturities, Fair Value;
After 1 but within 5 years, fair value	281,000,000	239,000,000
After 5 but within 10 years, fair value	186,000,000	224,000,000
After 10 years, fair value	5,924,000,000	6,320,000,000
Total fair value	6,391,000,000	6,783,000,000
State and municipal securities
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount;
Due within 1 year, carrying value	4,000,000	4,000,000
After 1 but within 5 years, carrying value	43,000,000	43,000,000
After 5 but within 10 years, carrying value	64,000,000	31,000,000
After 10 years, carrying value	1,175,000,000	1,249,000,000
Total carrying value	1,286,000,000	1,327,000,000
Held-to-maturity Securities, Debt Maturities, Fair Value;
Due within 1 year, fair value	4,000,000	4,000,000
After 1 but within 5 years, fair value	49,000,000	46,000,000
After 5 but within 10 years, fair value	73,000,000	30,000,000
After 10 years, fair value	1,180,000,000	1,243,000,000
Total fair value	1,306,000,000	1,323,000,000
All Other
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount;
Due within 1 year, carrying value	11,000,000	21,000,000
After 1 but within 5 years, carrying value	644,000,000	470,000,000
After 5 but within 10 years, carrying value	554,000,000	1,404,000,000
After 10 years, carrying value	808,000,000	831,000,000
Total carrying value	2,017,000,000	2,726,000,000
Held-to-maturity Securities, Debt Maturities, Fair Value;
Due within 1 year, fair value	11,000,000	21,000,000
After 1 but within 5 years, fair value	657,000,000	438,000,000
After 5 but within 10 years, fair value	550,000,000	1,182,000,000
After 10 years, fair value	741,000,000	753,000,000
Total fair value	$ 1,959,000,000	$ 2,394,000,000