INVESTMENTS - Fair Value of AFS Securities (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
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	$ 45,431	$ 74,026
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	311	404
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	19,372	24,821
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	1,205	1,361
Total fair value of available for sale securities that have been in an unrealized loss position	64,803	98,847
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	1,516	1,765
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	3,521	4,198
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	14	30
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	3,176	5,547
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	79	129
Total fair value of available for sale securities that have been in an unrealized loss position	6,697	9,745
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	93	159
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	5
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	2	2
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	3	7
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	1,333	1,276
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	219	199
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	2	4
Total fair value of available for sale securities that have been in an unrealized loss position	1,552	1,475
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	5	7
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	54	124
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	0	1
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	60	136
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	1	2
Total fair value of available for sale securities that have been in an unrealized loss position	114	260
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	1	3
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	4,909	5,603
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	17	34
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	3,457	5,884
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	82	135
Total fair value of available for sale securities that have been in an unrealized loss position	8,366	11,487
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	99	169
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	15,077	36,581
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	67	119
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	915	1,013
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	2	8
Total fair value of available for sale securities that have been in an unrealized loss position	15,992	37,594
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	69	127
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	644	5,698
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	2	9
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	0	754
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	0	4
Total fair value of available for sale securities that have been in an unrealized loss position	644	6,452
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	2	13
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	15,721	42,279
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	69	128
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	915	1,767
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	2	12
Total fair value of available for sale securities that have been in an unrealized loss position	16,636	44,046
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	71	140
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	303	386
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	11	15
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	5,162	5,802
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	906	962
Total fair value of available for sale securities that have been in an unrealized loss position	5,465	6,188
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	917	977
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	18,853	18,495
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	160	147
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	5,261	5,984
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	123	139
Total fair value of available for sale securities that have been in an unrealized loss position	24,114	24,479
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	283	286
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	3,710	3,511
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	38	63
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	900	1,350
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	16	28
Total fair value of available for sale securities that have been in an unrealized loss position	4,610	4,861
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	54	91
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	1,911	3,701
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	14	13
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	3,463	3,816
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	35	45
Total fair value of available for sale securities that have been in an unrealized loss position	5,374	7,517
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	49	58
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	24	51
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months	2	4
Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer	214	218
Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer	41	40
Total fair value of available for sale securities that have been in an unrealized loss position	238	269
Total gross unrealized losses of available for sale securities that have been in an unrealized loss position	$ 43	$ 44