INVESTMENTS (Details 5) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Held-to-maturity Securities, Continuous Unrealized Loss Position
Fair value less than 12 months	$ 1,158,000,000	$ 1,215,000,000
Gross unrecognized losses less than 12 months	92,000,000	134,000,000
Fair value 12 months or longer	6,039,000,000	7,242,000,000
Gross unrecognized losses 12 months or longer	588,000,000	1,031,000,000
Fair value, total	7,197,000,000	8,457,000,000
Gross unrecognized losses, total	680,000,000	1,165,000,000
Gross unrecognized losses 12 months or longer for securities reclassified from AFS investments	2,100,000,000	2,300,000,000
Mortgage-backed securities
Held-to-maturity Securities, Continuous Unrealized Loss Position
Fair value less than 12 months	981,000,000	735,000,000
Gross unrecognized losses less than 12 months	69,000,000	63,000,000
Fair value 12 months or longer	4,195,000,000	4,827,000,000
Gross unrecognized losses 12 months or longer	466,000,000	689,000,000
Fair value, total	5,176,000,000	5,562,000,000
Gross unrecognized losses, total	535,000,000	752,000,000
State and municipal securities
Held-to-maturity Securities, Continuous Unrealized Loss Position
Fair value 12 months or longer	634,000,000	682,000,000
Gross unrecognized losses 12 months or longer	70,000,000	72,000,000
Fair value, total	634,000,000	682,000,000
Gross unrecognized losses, total	70,000,000	72,000,000
Corporate
Held-to-maturity Securities, Continuous Unrealized Loss Position
Fair value 12 months or longer	606,000,000	1,427,000,000
Gross unrecognized losses 12 months or longer	1,000,000	254,000,000
Fair value, total	606,000,000	1,427,000,000
Gross unrecognized losses, total	1,000,000	254,000,000
Asset-backed securities
Held-to-maturity Securities, Continuous Unrealized Loss Position
Fair value less than 12 months	177,000,000	480,000,000
Gross unrecognized losses less than 12 months	23,000,000	71,000,000
Fair value 12 months or longer	604,000,000	306,000,000
Gross unrecognized losses 12 months or longer	51,000,000	16,000,000
Fair value, total	781,000,000	786,000,000
Gross unrecognized losses, total	$ 74,000,000	$ 87,000,000