INVESTMENTS - Debt Securities in HTM in Unrecognized Loss Position (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value
Less than 12 months	$ 2,923	$ 2,128
12 months or longer	4,201	15,359
Total	7,124	17,487
Held-to-maturity Securities, Continuous Unrealized Loss Position, Gross Recognized Losses
Less than 12 months	17	37
12 months or longer	89	357
Total	106	394
Unrealized (loss), other than temporary impairment, not credit loss, recorded in AOCI	(350)	(453)
Mortgage-backed securities
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value
Less than 12 months	695	935
12 months or longer	553	10,301
Total	1,248	11,236
Held-to-maturity Securities, Continuous Unrealized Loss Position, Gross Recognized Losses
Less than 12 months	3	1
12 months or longer	7	262
Total	10	263
State and municipal securities
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value
Less than 12 months	365	881
12 months or longer	1,435	1,826
Total	1,800	2,707
Held-to-maturity Securities, Continuous Unrealized Loss Position, Gross Recognized Losses
Less than 12 months	4	20
12 months or longer	73	67
Total	77	87
Foreign government
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value
Less than 12 months	1,853	180
12 months or longer	0	0
Total	1,853	180
Held-to-maturity Securities, Continuous Unrealized Loss Position, Gross Recognized Losses
Less than 12 months	9	3
12 months or longer	0	0
Total	9	3
Asset-backed securities
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value
Less than 12 months	10	132
12 months or longer	2,213	3,232
Total	2,223	3,364
Held-to-maturity Securities, Continuous Unrealized Loss Position, Gross Recognized Losses
Less than 12 months	1	13
12 months or longer	9	28
Total	$ 10	$ 41