INVESTMENTS - Debt Securities in HTM in Unrecognized Loss Position (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Held-to-maturity Securities, Continuous Unrealized Loss Position
Fair value less than 12 months	$ 898	$ 2,128
Gross unrecognized losses less than 12 months	32	37
Fair value 12 months or longer	7,132	15,359
Gross unrecognized losses 12 months or longer	286	357
Fair value, total	8,030	17,487
Gross unrecognized losses, total	318	394
Unrealized loss, other than temporary impairment, not credit loss, recorded in AOCI	(414)	(453)
Mortgage-backed securities
Held-to-maturity Securities, Continuous Unrealized Loss Position
Fair value less than 12 months	106	935
Gross unrecognized losses less than 12 months	2	1
Fair value 12 months or longer	633	10,301
Gross unrecognized losses 12 months or longer	159	262
Fair value, total	739	11,236
Gross unrecognized losses, total	161	263
State and municipal securities
Held-to-maturity Securities, Continuous Unrealized Loss Position
Fair value less than 12 months	610	881
Gross unrecognized losses less than 12 months	6	20
Fair value 12 months or longer	1,669	1,826
Gross unrecognized losses 12 months or longer	79	67
Fair value, total	2,279	2,707
Gross unrecognized losses, total	85	87
Foreign government
Held-to-maturity Securities, Continuous Unrealized Loss Position
Fair value less than 12 months	0	180
Gross unrecognized losses less than 12 months	0	3
Fair value 12 months or longer	0	0
Gross unrecognized losses 12 months or longer	0	0
Fair value, total	0	180
Gross unrecognized losses, total	0	3
Asset-backed securities
Held-to-maturity Securities, Continuous Unrealized Loss Position
Fair value less than 12 months	182	132
Gross unrecognized losses less than 12 months	24	13
Fair value 12 months or longer	4,830	3,232
Gross unrecognized losses 12 months or longer	48	28
Fair value, total	5,012	3,364
Gross unrecognized losses, total	$ 72	$ 41