FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Assets:
Available-for-sale securities	$ 76,702	$ 67,794
Asset derivatives	1,207	676
Other investments	276	176
Cash and cash equivalents	4,859	4,350
Total assets	83,044	72,996
Liabilities:
Liability derivatives	1,998	371
Total liabilities	1,998	371
Foreign currency swaps
Assets:
Asset derivatives	490	563
Liabilities:
Liability derivatives	230	314
Foreign currency forwards
Assets:
Asset derivatives	672	107
Liabilities:
Liability derivatives	1,717	49
Foreign currency options
Assets:
Asset derivatives	43	5
Liabilities:
Liability derivatives	51	8
Credit default swaps
Assets:
Asset derivatives	2	1
Fixed maturities
Assets:
Available-for-sale securities	73,760	65,349
Fixed maturities | Government and agencies
Assets:
Available-for-sale securities	26,214	19,276
Fixed maturities | Municipalities
Assets:
Available-for-sale securities	1,295	1,208
Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale securities	1,337	582
Fixed maturities | Public utilities
Assets:
Available-for-sale securities	7,683	7,479
Fixed maturities | Sovereign and supranational
Assets:
Available-for-sale securities	1,469	1,407
Fixed maturities | Banks/financial institutions
Assets:
Available-for-sale securities	6,063	6,019
Fixed maturities | Other corporate
Assets:
Available-for-sale securities	29,699	29,378
Perpetual securities
Assets:
Available-for-sale securities	1,633	1,947
Perpetual securities | Banks/financial institutions
Assets:
Available-for-sale securities	1,420	1,742
Perpetual securities | Other corporate
Assets:
Available-for-sale securities	213	205
Equity securities
Assets:
Available-for-sale securities	1,309	498
Level 1
Assets:
Available-for-sale securities	26,687	19,158
Asset derivatives	0	0
Other investments	276	176
Cash and cash equivalents	4,859	4,350
Total assets	31,822	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	25,387	18,669
Level 1 | Fixed maturities | Government and agencies
Assets:
Available-for-sale securities	25,387	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	1,300	489
Level 2
Assets:
Available-for-sale securities	49,773	48,387
Asset derivatives	1,080	574
Other investments	0	0
Cash and cash equivalents	0	0
Total assets	50,853	48,961
Liabilities:
Total liabilities	1,852	78
Level 2 | Foreign currency swaps
Assets:
Asset derivatives	365	462
Liabilities:
Liability derivatives	84	21
Level 2 | Foreign currency forwards
Assets:
Asset derivatives	672	107
Liabilities:
Liability derivatives	1,717	49
Level 2 | Foreign currency options
Assets:
Asset derivatives	43	5
Liabilities:
Liability derivatives	51	8
Level 2 | Credit default swaps
Assets:
Asset derivatives	0	0
Level 2 | Fixed maturities
Assets:
Available-for-sale securities	48,134	46,434
Level 2 | Fixed maturities | Government and agencies
Assets:
Available-for-sale securities	827	607
Level 2 | Fixed maturities | Municipalities
Assets:
Available-for-sale securities	1,295	1,208
Level 2 | Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale securities	1,139	362
Level 2 | Fixed maturities | Public utilities
Assets:
Available-for-sale securities	7,667	7,479
Level 2 | Fixed maturities | Sovereign and supranational
Assets:
Available-for-sale securities	1,469	1,407
Level 2 | Fixed maturities | Banks/financial institutions
Assets:
Available-for-sale securities	6,038	5,993
Level 2 | Fixed maturities | Other corporate
Assets:
Available-for-sale securities	29,699	29,378
Level 2 | Perpetual securities
Assets:
Available-for-sale securities	1,633	1,947
Level 2 | Perpetual securities | Banks/financial institutions
Assets:
Available-for-sale securities	1,420	1,742
Level 2 | Perpetual securities | Other corporate
Assets:
Available-for-sale securities	213	205
Level 2 | Equity securities
Assets:
Available-for-sale securities	6	6
Level 3
Assets:
Available-for-sale securities	242	249
Asset derivatives	127	102
Other investments	0	0
Cash and cash equivalents	0	0
Total assets	369	351
Liabilities:
Total liabilities	146	293
Level 3 | Foreign currency swaps
Assets:
Asset derivatives	125	101
Liabilities:
Liability derivatives	146	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	239	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	198	220
Level 3 | Fixed maturities | Public utilities
Assets:
Available-for-sale securities	16	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	25	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