FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Assets:
Available-for-sale Securities	$ 74,906	$ 67,794
Asset derivatives	1,144	676
Other Investments	198	176
Cash and cash equivalents	3,449	4,350
Total assets	79,697	72,996
Liabilities:
Liability derivatives	332	371
Total liabilities	332	371
Foreign currency swaps
Assets:
Asset derivatives	493	563
Liabilities:
Liability derivatives	272	314
Foreign currency forwards
Assets:
Asset derivatives	644	107
Liabilities:
Liability derivatives	36	49
Foreign currency options
Assets:
Asset derivatives	5	5
Liabilities:
Liability derivatives	24	8
Credit default swaps
Assets:
Asset derivatives	2	1
Fixed maturities
Assets:
Available-for-sale Securities	72,128	65,349
Fixed maturities | Government and agencies
Assets:
Available-for-sale Securities	23,781	19,276
Fixed maturities | Municipalities
Assets:
Available-for-sale Securities	1,270	1,208
Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale Securities	605	582
Fixed maturities | Public utilities
Assets:
Available-for-sale Securities	7,819	7,479
Fixed maturities | Sovereign and supranational
Assets:
Available-for-sale Securities	1,451	1,407
Fixed maturities | Banks/financial institutions
Assets:
Available-for-sale Securities	5,856	6,019
Fixed maturities | Other corporate
Assets:
Available-for-sale Securities	31,346	29,378
Perpetual securities
Assets:
Available-for-sale Securities	1,909	1,947
Perpetual securities | Banks/financial institutions
Assets:
Available-for-sale Securities	1,692	1,742
Perpetual securities | Other corporate
Assets:
Available-for-sale Securities	217	205
Equity securities
Assets:
Available-for-sale Securities	869	498
Level 1
Assets:
Available-for-sale Securities	23,935	19,158
Asset derivatives	0	0
Other Investments	198	176
Cash and cash equivalents	3,449	4,350
Total assets	27,582	23,684
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	0
Liabilities:
Liability derivatives	0	0
Level 1 | Credit default swaps
Assets:
Asset derivatives	0	0
Level 1 | Fixed maturities
Assets:
Available-for-sale Securities	23,075	18,669
Level 1 | Fixed maturities | Government and agencies
Assets:
Available-for-sale Securities	23,075	18,669
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	860	489
Level 2
Assets:
Available-for-sale Securities	50,705	48,387
Asset derivatives	1,030	574
Other Investments	0	0
Cash and cash equivalents	0	0
Total assets	51,735	48,961
Liabilities:
Total liabilities	157	78
Level 2 | Foreign currency swaps
Assets:
Asset derivatives	381	462
Liabilities:
Liability derivatives	97	21
Level 2 | Foreign currency forwards
Assets:
Asset derivatives	644	107
Liabilities:
Liability derivatives	36	49
Level 2 | Foreign currency options
Assets:
Asset derivatives	5	5
Liabilities:
Liability derivatives	24	8
Level 2 | Credit default swaps
Assets:
Asset derivatives	0	0
Level 2 | Fixed maturities
Assets:
Available-for-sale Securities	48,790	46,434
Level 2 | Fixed maturities | Government and agencies
Assets:
Available-for-sale Securities	706	607
Level 2 | Fixed maturities | Municipalities
Assets:
Available-for-sale Securities	1,270	1,208
Level 2 | Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale Securities	368	362
Level 2 | Fixed maturities | Public utilities
Assets:
Available-for-sale Securities	7,819	7,479
Level 2 | Fixed maturities | Sovereign and supranational
Assets:
Available-for-sale Securities	1,451	1,407
Level 2 | Fixed maturities | Banks/financial institutions
Assets:
Available-for-sale Securities	5,830	5,993
Level 2 | Fixed maturities | Other corporate
Assets:
Available-for-sale Securities	31,346	29,378
Level 2 | Perpetual securities
Assets:
Available-for-sale Securities	1,909	1,947
Level 2 | Perpetual securities | Banks/financial institutions
Assets:
Available-for-sale Securities	1,692	1,742
Level 2 | Perpetual securities | Other corporate
Assets:
Available-for-sale Securities	217	205
Level 2 | Equity securities
Assets:
Available-for-sale Securities	6	6
Level 3
Assets:
Available-for-sale Securities	266	249
Asset derivatives	114	102
Other Investments	0	0
Cash and cash equivalents	0	0
Total assets	380	351
Liabilities:
Total liabilities	175	293
Level 3 | Foreign currency swaps
Assets:
Asset derivatives	112	101
Liabilities:
Liability derivatives	175	293
Level 3 | Foreign currency forwards
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	0	0
Level 3 | Foreign currency options
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	0	0
Level 3 | Credit default swaps
Assets:
Asset derivatives	2	1
Level 3 | Fixed maturities
Assets:
Available-for-sale Securities	263	246
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	237	220
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	26
Level 3 | Fixed maturities | Other corporate
Assets:
Available-for-sale Securities	0	0
Level 3 | Perpetual securities
Assets:
Available-for-sale Securities	0	0
Level 3 | Perpetual securities | Banks/financial institutions
Assets:
Available-for-sale Securities	0	0
Level 3 | Perpetual securities | Other corporate
Assets:
Available-for-sale Securities	0	0
Level 3 | Equity securities
Assets:
Available-for-sale Securities	$ 3	$ 3