FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Assets:
Available-for-sale Securities	$ 83,799	$ 67,794
Asset derivatives	1,662	676
Other Investments	299	176
Cash and cash equivalents	5,270	4,350
Total assets	91,030	72,996
Liabilities:
Liability derivatives	601	371
Total liabilities	601	371
Foreign currency swaps
Assets:
Asset derivatives	460	563
Liabilities:
Liability derivatives	436	314
Foreign currency forwards
Assets:
Asset derivatives	1,189	107
Liabilities:
Liability derivatives	109	49
Foreign currency options
Assets:
Asset derivatives	10	5
Liabilities:
Liability derivatives	56	8
Credit default swaps
Assets:
Asset derivatives	3	1
Fixed maturities
Assets:
Available-for-sale Securities	80,527	65,349
Fixed maturities | Government and agencies
Assets:
Available-for-sale Securities	27,406	19,276
Fixed maturities | Municipalities
Assets:
Available-for-sale Securities	1,353	1,208
Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale Securities	1,228	582
Fixed maturities | Public utilities
Assets:
Available-for-sale Securities	8,509	7,479
Fixed maturities | Sovereign and supranational
Assets:
Available-for-sale Securities	1,598	1,407
Fixed maturities | Banks/financial institutions
Assets:
Available-for-sale Securities	6,344	6,019
Fixed maturities | Other corporate
Assets:
Available-for-sale Securities	34,089	29,378
Perpetual securities
Assets:
Available-for-sale Securities	1,994	1,947
Perpetual securities | Banks/financial institutions
Assets:
Available-for-sale Securities	1,768	1,742
Perpetual securities | Other corporate
Assets:
Available-for-sale Securities	226	205
Equity securities
Assets:
Available-for-sale Securities	1,278	498
Level 1
Assets:
Available-for-sale Securities	27,806	19,158
Asset derivatives	0	0
Other Investments	299	176
Cash and cash equivalents	5,270	4,350
Total assets	33,375	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	26,537	18,669
Level 1 | Fixed maturities | Government and agencies
Assets:
Available-for-sale Securities	26,537	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	1,269	489
Level 2
Assets:
Available-for-sale Securities	55,724	48,387
Asset derivatives	1,494	574
Other Investments	0	0
Cash and cash equivalents	0	0
Total assets	57,218	48,961
Liabilities:
Total liabilities	477	78
Level 2 | Foreign currency swaps
Assets:
Asset derivatives	295	462
Liabilities:
Liability derivatives	312	21
Level 2 | Foreign currency forwards
Assets:
Asset derivatives	1,189	107
Liabilities:
Liability derivatives	109	49
Level 2 | Foreign currency options
Assets:
Asset derivatives	10	5
Liabilities:
Liability derivatives	56	8
Level 2 | Credit default swaps
Assets:
Asset derivatives	0	0
Level 2 | Fixed maturities
Assets:
Available-for-sale Securities	53,724	46,434
Level 2 | Fixed maturities | Government and agencies
Assets:
Available-for-sale Securities	869	607
Level 2 | Fixed maturities | Municipalities
Assets:
Available-for-sale Securities	1,353	1,208
Level 2 | Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale Securities	988	362
Level 2 | Fixed maturities | Public utilities
Assets:
Available-for-sale Securities	8,509	7,479
Level 2 | Fixed maturities | Sovereign and supranational
Assets:
Available-for-sale Securities	1,598	1,407
Level 2 | Fixed maturities | Banks/financial institutions
Assets:
Available-for-sale Securities	6,318	5,993
Level 2 | Fixed maturities | Other corporate
Assets:
Available-for-sale Securities	34,089	29,378
Level 2 | Perpetual securities
Assets:
Available-for-sale Securities	1,994	1,947
Level 2 | Perpetual securities | Banks/financial institutions
Assets:
Available-for-sale Securities	1,768	1,742
Level 2 | Perpetual securities | Other corporate
Assets:
Available-for-sale Securities	226	205
Level 2 | Equity securities
Assets:
Available-for-sale Securities	6	6
Level 3
Assets:
Available-for-sale Securities	269	249
Asset derivatives	168	102
Other Investments	0	0
Cash and cash equivalents	0	0
Total assets	437	351
Liabilities:
Total liabilities	124	293
Level 3 | Foreign currency swaps
Assets:
Asset derivatives	165	101
Liabilities:
Liability derivatives	124	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	3	1
Level 3 | Fixed maturities
Assets:
Available-for-sale Securities	266	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	240	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