INVESTMENTS - Available-For-Sale Investments in Debt Securities, Perpetual Securities and Equity Securities (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	$ 58,661	$ 57,646
Gross Unrealized Gains	2,751	4,716
Gross Unrealized Losses	2,746	784
Fair Value	58,666	61,578
Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	55,378	53,413
Gross Unrealized Gains	2,633	4,453
Gross Unrealized Losses	2,201	613
Fair Value	55,810	57,253
Perpetual Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	3,266	4,213
Gross Unrealized Gains	113	259
Gross Unrealized Losses	545	170
Fair Value	2,834	4,302
Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	17	20
Gross Unrealized Gains	5	4
Gross Unrealized Losses	0	1
Fair Value	22	23
Yen Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	23,821	27,481
Gross Unrealized Gains	687	1,050
Gross Unrealized Losses	866	487
Fair Value	23,642	28,044
Dollar Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	31,557	25,932
Gross Unrealized Gains	1,946	3,403
Gross Unrealized Losses	1,335	126
Fair Value	32,168	29,209
Japan government and agencies | Yen Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	12,100	12,612
Gross Unrealized Gains	277	349
Gross Unrealized Losses	79	81
Fair Value	12,298	12,880
Mortgage- and asset-backed Securities | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	895	1,031
Mortgage- and asset-backed Securities | Yen Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	624	746
Gross Unrealized Gains	30	40
Gross Unrealized Losses	1	1
Fair Value	653	785
Mortgage- and asset-backed Securities | Dollar Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	189	188
Gross Unrealized Gains	53	58
Gross Unrealized Losses	0	0
Fair Value	242	246
Public Utilities | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	7,866	8,497
Public Utilities | Yen Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	2,793	3,608
Gross Unrealized Gains	74	116
Gross Unrealized Losses	112	72
Fair Value	2,755	3,652
Public Utilities | Dollar Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	4,887	4,204
Gross Unrealized Gains	392	658
Gross Unrealized Losses	168	17
Fair Value	5,111	4,845
Sovereign and Supranational | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	1,661	2,072
Sovereign and Supranational | Yen Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	1,047	1,404
Gross Unrealized Gains	70	71
Gross Unrealized Losses	1	0
Fair Value	1,116	1,475
Sovereign and Supranational | Dollar Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	468	476
Gross Unrealized Gains	81	123
Gross Unrealized Losses	4	2
Fair Value	545	597
Banks/financial Institutions | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	6,694	7,634
Banks/financial Institutions | Perpetual Securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	2,631	3,950
Banks/financial Institutions | Yen Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	3,064	3,455
Gross Unrealized Gains	126	233
Gross Unrealized Losses	370	180
Fair Value	2,820	3,508
Banks/financial Institutions | Yen Denominated | Perpetual Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	2,786	3,635
Gross Unrealized Gains	91	193
Gross Unrealized Losses	461	161
Fair Value	2,416	3,667
Banks/financial Institutions | Dollar Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	3,592	3,626
Gross Unrealized Gains	328	506
Gross Unrealized Losses	46	6
Fair Value	3,874	4,126
Banks/financial Institutions | Dollar Denominated | Perpetual Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	208	269
Gross Unrealized Gains	22	23
Gross Unrealized Losses	15	9
Fair Value	215	283
Other Corporate | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	25,201	23,827
Other Corporate | Perpetual Securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	203	352
Other Corporate | Yen Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	4,193	5,656
Gross Unrealized Gains	110	241
Gross Unrealized Losses	303	153
Fair Value	4,000	5,744
Other Corporate | Yen Denominated | Perpetual Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	272	309
Gross Unrealized Gains	0	43
Gross Unrealized Losses	69	0
Fair Value	203	352
Other Corporate | Dollar Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	21,309	16,300
Gross Unrealized Gains	999	1,878
Gross Unrealized Losses	1,107	95
Fair Value	21,201	18,083
U.S. Government and Agencies | Dollar Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	95	93
Gross Unrealized Gains	11	24
Gross Unrealized Losses	2	0
Fair Value	104	117
Municipalities | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	1,091	1,195
Municipalities | Dollar Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	1,017	1,045
Gross Unrealized Gains	82	156
Gross Unrealized Losses	8	6
Fair Value	$ 1,091	$ 1,195