INVESTMENTS - Fair Value of AFS Securities (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Fair value
Less than 12 months	$ 38,917	$ 133,606
12 months or longer	22,797	17,537
Total	61,714	151,143
Gross unrealized losses
Less than 12 months	262	1,334
12 months or longer	939	1,107
Total	1,201	2,441
Mortgage-backed securities - U.S. agency-sponsored
Fair value
Less than 12 months	2,325	17,816
12 months or longer	1,925	2,618
Total	4,250	20,434
Gross unrealized losses
Less than 12 months	10	141
12 months or longer	61	96
Total	71	237
Mortgage-backed securities - Prime
Fair value
Less than 12 months		0
12 months or longer		1
Total		1
Gross unrealized losses
Less than 12 months		0
12 months or longer		0
Total		0
Mortgage-backed securities - Non-U.S. residential
Fair value
Less than 12 months	45	2,217
12 months or longer	1,899	825
Total	1,944	3,042
Gross unrealized losses
Less than 12 months	0	7
12 months or longer	10	4
Total	10	11
Mortgage-backed securities - Commercial
Fair value
Less than 12 months	38	291
12 months or longer	44	55
Total	82	346
Gross unrealized losses
Less than 12 months	0	3
12 months or longer	1	1
Total	1	4
Mortgage-backed securities
Fair value
Less than 12 months	2,408	20,324
12 months or longer	3,868	3,499
Total	6,276	23,823
Gross unrealized losses
Less than 12 months	10	151
12 months or longer	72	101
Total	82	252
U.S. Treasury
Fair value
Less than 12 months	7,895	59,384
12 months or longer	175	1,204
Total	8,070	60,588
Gross unrealized losses
Less than 12 months	33	505
12 months or longer	0	10
Total	33	515
Agency obligations
Fair value
Less than 12 months	1,450	6,716
12 months or longer	131	196
Total	1,581	6,912
Gross unrealized losses
Less than 12 months	3	30
12 months or longer	3	7
Total	6	37
U.S. Treasury and federal agency
Fair value
Less than 12 months	9,345	66,100
12 months or longer	306	1,400
Total	9,651	67,500
Gross unrealized losses
Less than 12 months	36	535
12 months or longer	3	17
Total	39	552
State and municipal securities
Fair value
Less than 12 months	302	635
12 months or longer	3,632	4,450
Total	3,934	5,085
Gross unrealized losses
Less than 12 months	14	26
12 months or longer	699	746
Total	713	772
Foreign government
Fair value
Less than 12 months	23,678	34,053
12 months or longer	8,230	4,021
Total	31,908	38,074
Gross unrealized losses
Less than 12 months	116	371
12 months or longer	85	108
Total	201	479
Corporate
Fair value
Less than 12 months	2,625	7,024
12 months or longer	1,831	1,919
Total	4,456	8,943
Gross unrealized losses
Less than 12 months	84	190
12 months or longer	48	101
Total	132	291
Asset-backed securities
Fair value
Less than 12 months	522	5,311
12 months or longer	4,917	2,247
Total	5,439	7,558
Gross unrealized losses
Less than 12 months	0	58
12 months or longer	32	34
Total	32	92
Other
Fair value
Less than 12 months	25	27
12 months or longer	0	0
Total	25	27
Gross unrealized losses
Less than 12 months	0	0
12 months or longer	0	0
Total	0	0
Equity securities
Fair value
Less than 12 months	12	132
12 months or longer	13	1
Total	25	133
Gross unrealized losses
Less than 12 months	2	3
12 months or longer	0	0
Total	$ 2	$ 3