FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets by Pricing Source, Available-for-sale Securities (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	$ 68,270	$ 61,038
Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	18,702	14,942
Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	49,167	45,649
Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	401	447
Fixed Maturities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	65,573	58,070
Fixed Maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	18,683	14,928
Fixed Maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	46,641	42,750
Fixed Maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	249	392
Perpetual securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	2,669	2,947
Perpetual securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Perpetual securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	2,520	2,895
Perpetual securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	149	52
Equity securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	28	21
Equity securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	19	14
Equity securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	6	4
Equity securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	3	3
Equity securities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	25	18
Equity securities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	19	14
Equity securities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	6	4
Equity securities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Equity securities | Net asset value valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	3	3
Equity securities | Net asset value valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Equity securities | Net asset value valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Equity securities | Net asset value valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	3	3
Government and agencies | Fixed Maturities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	19,198	15,432
Government and agencies | Fixed Maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	18,683	14,928
Government and agencies | Fixed Maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	515	504
Government and agencies | Fixed Maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Government and agencies | Fixed Maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	19,198	15,432
Government and agencies | Fixed Maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	18,683	14,928
Government and agencies | Fixed Maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	515	504
Government and agencies | Fixed Maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Municipalities | Fixed Maturities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	1,257	1,051
Municipalities | Fixed Maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Municipalities | Fixed Maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	1,257	1,051
Municipalities | Fixed Maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Municipalities | Fixed Maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	1,257	1,051
Municipalities | Fixed Maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Municipalities | Fixed Maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	1,257	1,051
Municipalities | Fixed Maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Mortgage- and asset-backed securities | Fixed Maturities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	602	771
Mortgage- and asset-backed securities | Fixed Maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Mortgage- and asset-backed securities | Fixed Maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	379	402
Mortgage- and asset-backed securities | Fixed Maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	223	369
Mortgage- and asset-backed securities | Fixed Maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	379	402
Mortgage- and asset-backed securities | Fixed Maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Mortgage- and asset-backed securities | Fixed Maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	379	402
Mortgage- and asset-backed securities | Fixed Maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Mortgage- and asset-backed securities | Fixed Maturities | Consensus pricing valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	223	369
Mortgage- and asset-backed securities | Fixed Maturities | Consensus pricing valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Mortgage- and asset-backed securities | Fixed Maturities | Consensus pricing valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Mortgage- and asset-backed securities | Fixed Maturities | Consensus pricing valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	223	369
Public utilities | Fixed Maturities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	7,897	7,562
Public utilities | Fixed Maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Public utilities | Fixed Maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	7,897	7,562
Public utilities | Fixed Maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Public utilities | Fixed Maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	7,897	7,562
Public utilities | Fixed Maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Public utilities | Fixed Maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	7,897	7,562
Public utilities | Fixed Maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Sovereign and supranational | Fixed Maturities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	1,416	1,523
Sovereign and supranational | Fixed Maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Sovereign and supranational | Fixed Maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	1,416	1,523
Sovereign and supranational | Fixed Maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Sovereign and supranational | Fixed Maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	1,416	1,523
Sovereign and supranational | Fixed Maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Sovereign and supranational | Fixed Maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	1,416	1,523
Sovereign and supranational | Fixed Maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Banks/financial Institutions | Fixed Maturities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	6,598	6,509
Banks/financial Institutions | Fixed Maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Banks/financial Institutions | Fixed Maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	6,572	6,486
Banks/financial Institutions | Fixed Maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	26	23
Banks/financial Institutions | Fixed Maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	6,514	6,486
Banks/financial Institutions | Fixed Maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Banks/financial Institutions | Fixed Maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	6,514	6,486
Banks/financial Institutions | Fixed Maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Banks/financial Institutions | Fixed Maturities | Consensus pricing valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	84	23
Banks/financial Institutions | Fixed Maturities | Consensus pricing valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Banks/financial Institutions | Fixed Maturities | Consensus pricing valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	58	0
Banks/financial Institutions | Fixed Maturities | Consensus pricing valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	26	23
Banks/financial Institutions | Perpetual securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	2,438	2,738
Banks/financial Institutions | Perpetual securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Banks/financial Institutions | Perpetual securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	2,289	2,686
Banks/financial Institutions | Perpetual securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	149	52
Banks/financial Institutions | Perpetual securities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	2,289	2,738
Banks/financial Institutions | Perpetual securities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Banks/financial Institutions | Perpetual securities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	2,289	2,686
Banks/financial Institutions | Perpetual securities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	52
Banks/financial Institutions | Perpetual securities | Consensus pricing valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	149
Banks/financial Institutions | Perpetual securities | Consensus pricing valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0
Banks/financial Institutions | Perpetual securities | Consensus pricing valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0
Banks/financial Institutions | Perpetual securities | Consensus pricing valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	149	52
Other corporate | Fixed Maturities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	28,605	25,222
Other corporate | Fixed Maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Other corporate | Fixed Maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	28,605	25,222
Other corporate | Fixed Maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Other corporate | Fixed Maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	28,605	25,220
Other corporate | Fixed Maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Other corporate | Fixed Maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	28,605	25,220
Other corporate | Fixed Maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Other corporate | Fixed Maturities | Consensus pricing valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities		2
Other corporate | Fixed Maturities | Consensus pricing valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities		0
Other corporate | Fixed Maturities | Consensus pricing valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities		2
Other corporate | Fixed Maturities | Consensus pricing valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities		0
Other corporate | Perpetual securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	231	209
Other corporate | Perpetual securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Other corporate | Perpetual securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	231	209
Other corporate | Perpetual securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Other corporate | Perpetual securities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	231	209
Other corporate | Perpetual securities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	0	0
Other corporate | Perpetual securities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	231	209
Other corporate | Perpetual securities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale Securities	$ 0	$ 0