INVESTMENTS - Held-to-Maturity Investments in Debt Securities (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	$ 42,718	$ 54,426
Gross Unrealized Gains	1,322	1,213
Gross Unrealized Losses	1,279	798
Fair Value	42,761	54,841
Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	42,718	54,426
Fair Value	42,761	54,841
Yen Denominated | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	42,718	54,426
Gross Unrealized Gains	1,322	1,213
Gross Unrealized Losses	1,279	798
Fair Value	42,761	54,841
Japan government and agencies | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	23,946	32,043
Fair Value	24,682	32,332
Japan government and agencies | Yen Denominated | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	23,946	32,043
Gross Unrealized Gains	741	356
Gross Unrealized Losses	5	67
Fair Value	24,682	32,332
Municipalities | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	429	492
Fair Value	467	520
Municipalities | Yen Denominated | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	429	492
Gross Unrealized Gains	38	30
Gross Unrealized Losses	0	2
Fair Value	467	520
Mortgage- and asset-backed Securities | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	67	90
Fair Value	70	94
Mortgage- and asset-backed Securities | Yen Denominated | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	67	90
Gross Unrealized Gains	3	4
Gross Unrealized Losses	0	0
Fair Value	70	94
Public Utilities | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	4,323	4,924
Fair Value	4,192	5,051
Public Utilities | Yen Denominated | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	4,323	4,924
Gross Unrealized Gains	127	233
Gross Unrealized Losses	258	106
Fair Value	4,192	5,051
Sovereign and Supranational | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	2,817	3,209
Fair Value	2,844	3,317
Sovereign and Supranational | Yen Denominated | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	2,817	3,209
Gross Unrealized Gains	127	192
Gross Unrealized Losses	100	84
Fair Value	2,844	3,317
Banks/financial Institutions | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	7,222	9,211
Fair Value	6,632	8,991
Banks/financial Institutions | Yen Denominated | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	7,222	9,211
Gross Unrealized Gains	101	211
Gross Unrealized Losses	691	431
Fair Value	6,632	8,991
Other Corporate | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	3,914	4,457
Fair Value	3,874	4,536
Other Corporate | Yen Denominated | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	3,914	4,457
Gross Unrealized Gains	185	187
Gross Unrealized Losses	225	108
Fair Value	$ 3,874	$ 4,536