INVESTMENTS - Debt Securities in HTM in Unrecognized Loss Position (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Held-to-maturity Securities, Continuous Unrealized Loss Position
Fair value less than 12 months	$ 2,905	$ 2,541
Gross unrecognized losses less than 12 months	64	35
Fair value 12 months or longer	10,163	1,622
Gross unrecognized losses 12 months or longer	467	326
Fair value, total	13,068	4,163
Gross unrecognized losses, total	531	361
Unrealized loss, other than temporary impairment, not credit loss, recorded in AOCI	(586)	(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	8,638	1,134
Gross unrecognized losses 12 months or longer	402	294
Fair value, total	8,638	1,138
Gross unrecognized losses, total	402	294
State and municipal securities
Held-to-maturity Securities, Continuous Unrealized Loss Position
Fair value less than 12 months	2,905	2,528
Gross unrecognized losses less than 12 months	64	34
Fair value 12 months or longer	1,519	314
Gross unrecognized losses 12 months or longer	64	23
Fair value, total	4,424	2,842
Gross unrecognized losses, total	128	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	6	174
Gross unrecognized losses 12 months or longer	1	9
Fair value, total	6	183
Gross unrecognized losses, total	$ 1	$ 10