INVESTMENTS - Fair Value of AFS Securities (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Available for Sale Securities Continuous Unrealized Loss Position
Fair value of available for sale securities that have been in an unrealized loss position for less than twelve months	$ 41,731	$ 133,606
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	507	1,334
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	17,004	17,537
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	1,034	1,107
Total fair value of available for sale securities that have been in an unrealized loss position	58,735	151,143
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	1,541	2,441
Mortgage-backed securities - U.S. agency-sponsored
Available for Sale Securities Continuous Unrealized Loss Position
Fair value of available for sale securities that have been in an unrealized loss position for less than twelve months	4,069	17,816
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	22	141
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	2,487	2,618
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	68	96
Total fair value of available for sale securities that have been in an unrealized loss position	6,556	20,434
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	90	237
Mortgage-backed securities - Prime
Available for Sale Securities Continuous Unrealized Loss Position
Fair value of available for sale securities that have been in an unrealized loss position for less than twelve months	1	0
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	0	0
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	1	1
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	0	0
Total fair value of available for sale securities that have been in an unrealized loss position	2	1
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	0	0
Mortgage-backed securities - Non-U.S. residential
Available for Sale Securities Continuous Unrealized Loss Position
Fair value of available for sale securities that have been in an unrealized loss position for less than twelve months	1,909	2,217
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	13	7
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	1,047	825
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	12	4
Total fair value of available for sale securities that have been in an unrealized loss position	2,956	3,042
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	25	11
Mortgage-backed securities - Commercial
Available for Sale Securities Continuous Unrealized Loss Position
Fair value of available for sale securities that have been in an unrealized loss position for less than twelve months	64	291
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	0	3
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	50	55
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	1	1
Total fair value of available for sale securities that have been in an unrealized loss position	114	346
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	1	4
Mortgage-backed securities
Available for Sale Securities Continuous Unrealized Loss Position
Fair value of available for sale securities that have been in an unrealized loss position for less than twelve months	6,043	20,324
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	35	151
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	3,585	3,499
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	81	101
Total fair value of available for sale securities that have been in an unrealized loss position	9,628	23,823
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	116	252
U.S. Treasury
Available for Sale Securities Continuous Unrealized Loss Position
Fair value of available for sale securities that have been in an unrealized loss position for less than twelve months	1,487	59,384
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	7	505
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	156	1,204
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	0	10
Total fair value of available for sale securities that have been in an unrealized loss position	1,643	60,588
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	7	515
Agency obligations
Available for Sale Securities Continuous Unrealized Loss Position
Fair value of available for sale securities that have been in an unrealized loss position for less than twelve months	162	6,716
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	0	30
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	192	196
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	7	7
Total fair value of available for sale securities that have been in an unrealized loss position	354	6,912
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	7	37
U.S. Treasury and federal agency securities
Available for Sale Securities Continuous Unrealized Loss Position
Fair value of available for sale securities that have been in an unrealized loss position for less than twelve months	1,649	66,100
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	7	535
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	348	1,400
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	7	17
Total fair value of available for sale securities that have been in an unrealized loss position	1,997	67,500
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	14	552
State and municipal securities
Available for Sale Securities Continuous Unrealized Loss Position
Fair value of available for sale securities that have been in an unrealized loss position for less than twelve months	341	635
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	19	26
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	4,456	4,450
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	748	746
Total fair value of available for sale securities that have been in an unrealized loss position	4,797	5,085
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	767	772
Foreign government
Available for Sale Securities Continuous Unrealized Loss Position
Fair value of available for sale securities that have been in an unrealized loss position for less than twelve months	24,755	35,491
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	298	429
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	4,784	4,642
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	125	164
Total fair value of available for sale securities that have been in an unrealized loss position	29,539	40,133
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	423	593
Corporate
Available for Sale Securities Continuous Unrealized Loss Position
Fair value of available for sale securities that have been in an unrealized loss position for less than twelve months	4,359	5,586
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	73	132
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	1,303	1,298
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	36	45
Total fair value of available for sale securities that have been in an unrealized loss position	5,662	6,884
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	109	177
Asset-backed securities
Available for Sale Securities Continuous Unrealized Loss Position
Fair value of available for sale securities that have been in an unrealized loss position for less than twelve months	4,567	5,311
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	72	58
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	2,527	2,247
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	37	34
Total fair value of available for sale securities that have been in an unrealized loss position	7,094	7,558
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	109	92
Other debt securities
Available for Sale Securities Continuous Unrealized Loss Position
Fair value of available for sale securities that have been in an unrealized loss position for less than twelve months		27
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months		0
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer		0
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer		0
Total fair value of available for sale securities that have been in an unrealized loss position		27
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position		0
Equity securities
Available for Sale Securities Continuous Unrealized Loss Position
Fair value of available for sale securities that have been in an unrealized loss position for less than twelve months	17	132
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	3	3
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	1	1
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	0	0
Total fair value of available for sale securities that have been in an unrealized loss position	18	133
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	$ 3	$ 3