FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Assets:
Available-for-sale Securities	$ 68,270	$ 61,038
Asset derivatives	802	488
Other Investments	171	463
Cash and cash equivalents	4,658	2,543
Assets, fair value	73,901	64,532
Liabilities:
Liability derivatives	2,423	837
Total Liabilities	2,423	837
Foreign currency swaps
Assets:
Asset derivatives	746	445
Liabilities:
Liability derivatives	318	218
Foreign currency forwards
Assets:
Asset derivatives	56	17
Liabilities:
Liability derivatives	1,912	582
Foreign currency options
Assets:
Asset derivatives		4
Liabilities:
Liability derivatives	33	1
Credit default swaps
Assets:
Asset derivatives		1
Liabilities:
Liability derivatives		4
Interest rate swaps
Assets:
Asset derivatives		1
Interest rate swaptions
Assets:
Asset derivatives		20
Liabilities:
Liability derivatives	160	32
Fixed Maturities
Assets:
Available-for-sale Securities	65,573	58,070
Fixed Maturities | Government and agencies
Assets:
Available-for-sale Securities	19,198	15,432
Fixed Maturities | Municipalities
Assets:
Available-for-sale Securities	1,257	1,051
Fixed Maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale Securities	602	771
Fixed Maturities | Public utilities
Assets:
Available-for-sale Securities	7,897	7,562
Fixed Maturities | Sovereign and supranational
Assets:
Available-for-sale Securities	1,416	1,523
Fixed Maturities | Banks/financial Institutions
Assets:
Available-for-sale Securities	6,598	6,509
Fixed Maturities | Other corporate
Assets:
Available-for-sale Securities	28,605	25,222
Perpetual securities
Assets:
Available-for-sale Securities	2,669	2,947
Perpetual securities | Banks/financial Institutions
Assets:
Available-for-sale Securities	2,438	2,738
Perpetual securities | Other corporate
Assets:
Available-for-sale Securities	231	209
Equity securities
Assets:
Available-for-sale Securities	28	21
Level 1
Assets:
Available-for-sale Securities	18,702	14,942
Asset derivatives	0	0
Other Investments	171	463
Cash and cash equivalents	4,658	2,543
Assets, fair value	23,531	17,948
Liabilities:
Total Liabilities	0	0
Level 1 | Foreign currency swaps
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	0	0
Level 1 | Foreign currency forwards
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	0	0
Level 1 | Foreign currency options
Assets:
Asset derivatives		0
Liabilities:
Liability derivatives	0	0
Level 1 | Credit default swaps
Assets:
Asset derivatives		0
Liabilities:
Liability derivatives		0
Level 1 | Interest rate swaps
Assets:
Asset derivatives		0
Level 1 | Interest rate swaptions
Assets:
Asset derivatives		0
Liabilities:
Liability derivatives	0	0
Level 1 | Fixed Maturities
Assets:
Available-for-sale Securities	18,683	14,928
Level 1 | Fixed Maturities | Government and agencies
Assets:
Available-for-sale Securities	18,683	14,928
Level 1 | Fixed Maturities | Municipalities
Assets:
Available-for-sale Securities	0	0
Level 1 | Fixed Maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale Securities	0	0
Level 1 | Fixed Maturities | Public utilities
Assets:
Available-for-sale Securities	0	0
Level 1 | Fixed Maturities | Sovereign and supranational
Assets:
Available-for-sale Securities	0	0
Level 1 | Fixed Maturities | Banks/financial Institutions
Assets:
Available-for-sale Securities	0	0
Level 1 | Fixed Maturities | Other corporate
Assets:
Available-for-sale Securities	0	0
Level 1 | Perpetual securities
Assets:
Available-for-sale Securities	0	0
Level 1 | Perpetual securities | Banks/financial Institutions
Assets:
Available-for-sale Securities	0	0
Level 1 | Perpetual securities | Other corporate
Assets:
Available-for-sale Securities	0	0
Level 1 | Equity securities
Assets:
Available-for-sale Securities	19	14
Level 2
Assets:
Available-for-sale Securities	49,167	45,649
Asset derivatives	696	382
Other Investments	0	0
Cash and cash equivalents	0	0
Assets, fair value	49,863	46,031
Liabilities:
Total Liabilities	2,105	630
Level 2 | Foreign currency swaps
Assets:
Asset derivatives	640	341
Liabilities:
Liability derivatives	0	15
Level 2 | Foreign currency forwards
Assets:
Asset derivatives	56	17
Liabilities:
Liability derivatives	1,912	582
Level 2 | Foreign currency options
Assets:
Asset derivatives		4
Liabilities:
Liability derivatives	33	1
Level 2 | Credit default swaps
Assets:
Asset derivatives		0
Liabilities:
Liability derivatives		0
Level 2 | Interest rate swaps
Assets:
Asset derivatives		0
Level 2 | Interest rate swaptions
Assets:
Asset derivatives		20
Liabilities:
Liability derivatives	160	32
Level 2 | Fixed Maturities
Assets:
Available-for-sale Securities	46,641	42,750
Level 2 | Fixed Maturities | Government and agencies
Assets:
Available-for-sale Securities	515	504
Level 2 | Fixed Maturities | Municipalities
Assets:
Available-for-sale Securities	1,257	1,051
Level 2 | Fixed Maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale Securities	379	402
Level 2 | Fixed Maturities | Public utilities
Assets:
Available-for-sale Securities	7,897	7,562
Level 2 | Fixed Maturities | Sovereign and supranational
Assets:
Available-for-sale Securities	1,416	1,523
Level 2 | Fixed Maturities | Banks/financial Institutions
Assets:
Available-for-sale Securities	6,572	6,486
Level 2 | Fixed Maturities | Other corporate
Assets:
Available-for-sale Securities	28,605	25,222
Level 2 | Perpetual securities
Assets:
Available-for-sale Securities	2,520	2,895
Level 2 | Perpetual securities | Banks/financial Institutions
Assets:
Available-for-sale Securities	2,289	2,686
Level 2 | Perpetual securities | Other corporate
Assets:
Available-for-sale Securities	231	209
Level 2 | Equity securities
Assets:
Available-for-sale Securities	6	4
Level 3
Assets:
Available-for-sale Securities	401	447
Asset derivatives	106	106
Other Investments	0	0
Cash and cash equivalents	0	0
Assets, fair value	507	553
Liabilities:
Total Liabilities	318	207
Level 3 | Foreign currency swaps
Assets:
Asset derivatives	106	104
Liabilities:
Liability derivatives	318	203
Level 3 | Foreign currency forwards
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	0	0
Level 3 | Foreign currency options
Assets:
Asset derivatives		0
Liabilities:
Liability derivatives	0	0
Level 3 | Credit default swaps
Assets:
Asset derivatives		1
Liabilities:
Liability derivatives		4
Level 3 | Interest rate swaps
Assets:
Asset derivatives		1
Level 3 | Interest rate swaptions
Assets:
Asset derivatives		0
Liabilities:
Liability derivatives	0	0
Level 3 | Fixed Maturities
Assets:
Available-for-sale Securities	249	392
Level 3 | Fixed Maturities | Government and agencies
Assets:
Available-for-sale Securities	0	0
Level 3 | Fixed Maturities | Municipalities
Assets:
Available-for-sale Securities	0	0
Level 3 | Fixed Maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale Securities	223	369
Level 3 | Fixed Maturities | Public utilities
Assets:
Available-for-sale Securities	0	0
Level 3 | Fixed Maturities | Sovereign and supranational
Assets:
Available-for-sale Securities	0	0
Level 3 | Fixed Maturities | Banks/financial Institutions
Assets:
Available-for-sale Securities	26	23
Level 3 | Fixed Maturities | Other corporate
Assets:
Available-for-sale Securities	0	0
Level 3 | Perpetual securities
Assets:
Available-for-sale Securities	149	52
Level 3 | Perpetual securities | Banks/financial Institutions
Assets:
Available-for-sale Securities	149	52
Level 3 | Perpetual securities | Other corporate
Assets:
Available-for-sale Securities	0	0
Level 3 | Equity securities
Assets:
Available-for-sale Securities	3	3
Consensus pricing valuation technique | Fixed Maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale Securities	223	369
Consensus pricing valuation technique | Fixed Maturities | Banks/financial Institutions
Assets:
Available-for-sale Securities	84	23
Consensus pricing valuation technique | Fixed Maturities | Other corporate
Assets:
Available-for-sale Securities		2
Consensus pricing valuation technique | Perpetual securities | Banks/financial Institutions
Assets:
Available-for-sale Securities	149
Consensus pricing valuation technique | Level 1 | Fixed Maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale Securities	0	0
Consensus pricing valuation technique | Level 1 | Fixed Maturities | Banks/financial Institutions
Assets:
Available-for-sale Securities	0	0
Consensus pricing valuation technique | Level 1 | Fixed Maturities | Other corporate
Assets:
Available-for-sale Securities		0
Consensus pricing valuation technique | Level 1 | Perpetual securities | Banks/financial Institutions
Assets:
Available-for-sale Securities	0
Consensus pricing valuation technique | Level 2 | Fixed Maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale Securities	0	0
Consensus pricing valuation technique | Level 2 | Fixed Maturities | Banks/financial Institutions
Assets:
Available-for-sale Securities	58	0
Consensus pricing valuation technique | Level 2 | Fixed Maturities | Other corporate
Assets:
Available-for-sale Securities		2
Consensus pricing valuation technique | Level 2 | Perpetual securities | Banks/financial Institutions
Assets:
Available-for-sale Securities	0
Consensus pricing valuation technique | Level 3 | Fixed Maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale Securities	223	369
Consensus pricing valuation technique | Level 3 | Fixed Maturities | Banks/financial Institutions
Assets:
Available-for-sale Securities	26	23
Consensus pricing valuation technique | Level 3 | Fixed Maturities | Other corporate
Assets:
Available-for-sale Securities		0
Consensus pricing valuation technique | Level 3 | Perpetual securities | Banks/financial Institutions
Assets:
Available-for-sale Securities	$ 149	$ 52