INVESTMENTS - Held-to-Maturity Investments in Debt Securities (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	$ 40,858	$ 44,415
Gross Unrealized Gains	2,464	2,041
Gross Unrealized Losses	506	610
Fair Value	42,816	45,846
Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	40,858	44,415
Fair Value	42,816	45,846
Yen Denominated | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	40,858	44,415
Gross Unrealized Gains	2,464	2,041
Gross Unrealized Losses	506	610
Fair Value	42,816	45,846
Japan government and agencies | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	23,461	27,362
Fair Value	25,129	28,708
Japan government and agencies | Yen Denominated | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	23,461	27,362
Gross Unrealized Gains	1,668	1,347
Gross Unrealized Losses	0	1
Fair Value	25,129	28,708
Municipalities | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	409	399
Fair Value	455	440
Municipalities | Yen Denominated | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	409	399
Gross Unrealized Gains	46	41
Gross Unrealized Losses	0	0
Fair Value	455	440
Mortgage- and asset-backed Securities | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	58	58
Fair Value	61	61
Mortgage- and asset-backed Securities | Yen Denominated | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	58	58
Gross Unrealized Gains	3	3
Gross Unrealized Losses	0	0
Fair Value	61	61
Public Utilities | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	3,993	3,900
Fair Value	4,075	3,928
Public Utilities | Yen Denominated | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	3,993	3,900
Gross Unrealized Gains	189	150
Gross Unrealized Losses	107	122
Fair Value	4,075	3,928
Sovereign and Supranational | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	3,011	2,941
Fair Value	3,118	3,040
Sovereign and Supranational | Yen Denominated | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	3,011	2,941
Gross Unrealized Gains	163	171
Gross Unrealized Losses	56	72
Fair Value	3,118	3,040
Banks/financial Institutions | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	6,398	6,310
Fair Value	6,277	6,128
Banks/financial Institutions | Yen Denominated | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	6,398	6,310
Gross Unrealized Gains	174	146
Gross Unrealized Losses	295	328
Fair Value	6,277	6,128
Other Corporate | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	3,528	3,445
Fair Value	3,701	3,541
Other Corporate | Yen Denominated | Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	3,528	3,445
Gross Unrealized Gains	221	183
Gross Unrealized Losses	48	87
Fair Value	$ 3,701	$ 3,541