INVESTMENTS - Available-For-Sale Investments in Debt Securities, Perpetual Securities and Equity Securities (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	$ 64,399	$ 59,515
Gross Unrealized Gains	4,434	3,659
Gross Unrealized Losses	1,515	2,136
Fair Value	67,318	61,038
Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	61,325	56,511
Gross Unrealized Gains	4,214	3,468
Gross Unrealized Losses	1,258	1,909
Fair Value	64,281	58,070
Perpetual securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	3,057	2,987
Gross Unrealized Gains	215	186
Gross Unrealized Losses	256	226
Fair Value	3,016	2,947
Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	17	17
Gross Unrealized Gains	5	5
Gross Unrealized Losses	1	1
Fair Value	21	21
Yen Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	28,733	25,488
Gross Unrealized Gains	1,281	1,016
Gross Unrealized Losses	408	506
Fair Value	29,606	25,998
Dollar Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	32,592	31,023
Gross Unrealized Gains	2,933	2,452
Gross Unrealized Losses	850	1,403
Fair Value	34,675	32,072
Japan government and agencies | Yen Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	18,152	14,936
Gross Unrealized Gains	608	431
Gross Unrealized Losses	3	33
Fair Value	18,757	15,334
Mortgage- and asset-backed Securities | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	666	771
Mortgage- and asset-backed Securities | Yen Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	444	558
Gross Unrealized Gains	33	29
Gross Unrealized Losses	0	0
Fair Value	477	587
Mortgage- and asset-backed Securities | Dollar Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	169	163
Gross Unrealized Gains	20	21
Gross Unrealized Losses	0	0
Fair Value	189	184
Public Utilities | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	7,926	7,562
Public Utilities | Yen Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	2,223	2,261
Gross Unrealized Gains	96	100
Gross Unrealized Losses	24	18
Fair Value	2,295	2,343
Public Utilities | Dollar Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	5,156	4,931
Gross Unrealized Gains	577	471
Gross Unrealized Losses	102	183
Fair Value	5,631	5,219
Sovereign and Supranational | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	1,544	1,523
Sovereign and Supranational | Yen Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	937	978
Gross Unrealized Gains	125	85
Gross Unrealized Losses	0	28
Fair Value	1,062	1,035
Sovereign and Supranational | Dollar Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	396	404
Gross Unrealized Gains	86	85
Gross Unrealized Losses	0	1
Fair Value	482	488
Banks/financial Institutions | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	6,792	6,509
Banks/financial Institutions | Perpetual securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	2,787	2,738
Banks/financial Institutions | Yen Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	2,926	2,799
Gross Unrealized Gains	235	220
Gross Unrealized Losses	218	242
Fair Value	2,943	2,777
Banks/financial Institutions | Yen Denominated | Perpetual securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	2,644	2,582
Gross Unrealized Gains	165	151
Gross Unrealized Losses	250	217
Fair Value	2,559	2,516
Banks/financial Institutions | Dollar Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	3,340	3,318
Gross Unrealized Gains	526	447
Gross Unrealized Losses	17	33
Fair Value	3,849	3,732
Banks/financial Institutions | Dollar Denominated | Perpetual securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	199	196
Gross Unrealized Gains	35	35
Gross Unrealized Losses	6	9
Fair Value	228	222
Other Corporate | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	27,350	25,222
Other Corporate | Perpetual securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	229	209
Other Corporate | Yen Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	4,051	3,956
Gross Unrealized Gains	184	151
Gross Unrealized Losses	163	185
Fair Value	4,072	3,922
Other Corporate | Yen Denominated | Perpetual securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	214	209
Gross Unrealized Gains	15	0
Gross Unrealized Losses	0	0
Fair Value	229	209
Other Corporate | Dollar Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	22,392	21,123
Gross Unrealized Gains	1,611	1,347
Gross Unrealized Losses	725	1,170
Fair Value	23,278	21,300
U.S. Government and Agencies | Dollar Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	141	92
Gross Unrealized Gains	10	10
Gross Unrealized Losses	2	4
Fair Value	149	98
Municipalities | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	1,097	1,051
Municipalities | Dollar Denominated | Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	998	992
Gross Unrealized Gains	103	71
Gross Unrealized Losses	4	12
Fair Value	$ 1,097	$ 1,051