INVESTMENTS - Debt Securities in HTM in Unrecognized Loss Position (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Fair Value
Less than 12 months	$ 13,774	$ 17,814
12 months or longer	10,749	19,328
Total	24,523	37,142
Gross Unrecognized Losses
Less than 12 months	55	190
12 months or longer	99	663
Total	154	853
Unrealized loss, other than temporary impairment, not credit loss, recorded in AOCI	(658)	(653)
Mortgage-backed securities
Fair Value
Less than 12 months	304	2,822
12 months or longer	9,980	18,086
Total	10,284	20,908
Gross Unrecognized Losses
Less than 12 months	1	20
12 months or longer	81	559
Total	82	579
State and municipal securities
Fair Value
Less than 12 months	9	981
12 months or longer	268	1,242
Total	277	2,223
Gross Unrecognized Losses
Less than 12 months	0	34
12 months or longer	13	104
Total	13	138
Foreign government
Fair Value
Less than 12 months	1,929	1,003
12 months or longer	0	0
Total	1,929	1,003
Gross Unrecognized Losses
Less than 12 months	8	24
12 months or longer	0	0
Total	8	24
Asset-backed securities
Fair Value
Less than 12 months	11,532	13,008
12 months or longer	501	0
Total	12,033	13,008
Gross Unrecognized Losses
Less than 12 months	46	112
12 months or longer	5	0
Total	$ 51	$ 112