INVESTMENTS - Debt Securities in HTM in Unrecognized Loss Position (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Held-to-maturity Securities, Continuous Unrealized Loss Position
Fair value less than 12 months	$ 2,756	$ 2,541
Gross unrecognized losses less than 12 months	48	35
Fair value 12 months or longer	491	1,622
Gross unrecognized losses 12 months or longer	319	326
Fair value, total	3,247	4,163
Gross unrecognized losses, total	367	361
Unrealized loss, other than temporary impairment, not credit loss, recorded in AOCI	(671)	(780)
Mortgage-backed securities
Held-to-maturity Securities, Continuous Unrealized Loss Position
Fair value less than 12 months	0	4
Gross unrecognized losses less than 12 months	0	0
Fair value 12 months or longer	271	1,134
Gross unrecognized losses 12 months or longer	296	294
Fair value, total	271	1,138
Gross unrecognized losses, total	296	294
State and municipal securities
Held-to-maturity Securities, Continuous Unrealized Loss Position
Fair value less than 12 months	2,756	2,528
Gross unrecognized losses less than 12 months	48	34
Fair value 12 months or longer	210	314
Gross unrecognized losses 12 months or longer	22	23
Fair value, total	2,966	2,842
Gross unrecognized losses, total	70	57
Asset-backed securities
Held-to-maturity Securities, Continuous Unrealized Loss Position
Fair value less than 12 months	0	9
Gross unrecognized losses less than 12 months	0	1
Fair value 12 months or longer	10	174
Gross unrecognized losses 12 months or longer	1	9
Fair value, total	10	183
Gross unrecognized losses, total	$ 1	$ 10