FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Assets:
Available-for-sale Securities	$ 83,003	$ 76,702
Asset derivatives	543	1,207
Other Investments	138	276
Cash and cash equivalents	4,264	4,859
Total assets	87,948	83,044
Liabilities:
Liability derivatives	1,121	1,998
Total liabilities	1,121	1,998
Foreign currency swaps
Assets:
Asset derivatives	307	490
Liabilities:
Liability derivatives	199	230
Foreign currency forwards
Assets:
Asset derivatives	214	672
Liabilities:
Liability derivatives	906	1,717
Foreign currency options
Assets:
Asset derivatives	20	43
Liabilities:
Liability derivatives	16	51
Credit default swaps
Assets:
Asset derivatives	2	2
Fixed maturities
Assets:
Available-for-sale Securities	79,757	73,760
Fixed maturities | Government and agencies
Assets:
Available-for-sale Securities	30,029	26,214
Fixed maturities | Municipalities
Assets:
Available-for-sale Securities	1,344	1,295
Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale Securities	480	1,337
Fixed maturities | Public utilities
Assets:
Available-for-sale Securities	8,004	7,683
Fixed maturities | Sovereign and supranational
Assets:
Available-for-sale Securities	2,074	1,469
Fixed maturities | Banks/financial institutions
Assets:
Available-for-sale Securities	6,796	6,063
Fixed maturities | Other corporate
Assets:
Available-for-sale Securities	31,030	29,699
Perpetual securities
Assets:
Available-for-sale Securities	1,843	1,633
Perpetual securities | Banks/financial institutions
Assets:
Available-for-sale Securities	1,615	1,420
Perpetual securities | Other corporate
Assets:
Available-for-sale Securities	228	213
Equity securities
Assets:
Available-for-sale Securities	1,403	1,309
Level 1
Assets:
Available-for-sale Securities	30,512	26,687
Asset derivatives	0	0
Other Investments	138	276
Cash and cash equivalents	4,264	4,859
Total assets	34,914	31,822
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	29,129	25,387
Level 1 | Fixed maturities | Government and agencies
Assets:
Available-for-sale Securities	29,129	25,387
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	1,383	1,300
Level 2
Assets:
Available-for-sale Securities	52,134	49,773
Asset derivatives	401	1,080
Other Investments	0	0
Cash and cash equivalents	0	0
Total assets	52,535	50,853
Liabilities:
Total liabilities	988	1,852
Level 2 | Foreign currency swaps
Assets:
Asset derivatives	167	365
Liabilities:
Liability derivatives	66	84
Level 2 | Foreign currency forwards
Assets:
Asset derivatives	214	672
Liabilities:
Liability derivatives	906	1,717
Level 2 | Foreign currency options
Assets:
Asset derivatives	20	43
Liabilities:
Liability derivatives	16	51
Level 2 | Credit default swaps
Assets:
Asset derivatives	0	0
Level 2 | Fixed maturities
Assets:
Available-for-sale Securities	50,285	48,134
Level 2 | Fixed maturities | Government and agencies
Assets:
Available-for-sale Securities	900	827
Level 2 | Fixed maturities | Municipalities
Assets:
Available-for-sale Securities	1,344	1,295
Level 2 | Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale Securities	292	1,139
Level 2 | Fixed maturities | Public utilities
Assets:
Available-for-sale Securities	7,951	7,667
Level 2 | Fixed maturities | Sovereign and supranational
Assets:
Available-for-sale Securities	2,074	1,469
Level 2 | Fixed maturities | Banks/financial institutions
Assets:
Available-for-sale Securities	6,771	6,038
Level 2 | Fixed maturities | Other corporate
Assets:
Available-for-sale Securities	30,953	29,699
Level 2 | Perpetual securities
Assets:
Available-for-sale Securities	1,843	1,633
Level 2 | Perpetual securities | Banks/financial institutions
Assets:
Available-for-sale Securities	1,615	1,420
Level 2 | Perpetual securities | Other corporate
Assets:
Available-for-sale Securities	228	213
Level 2 | Equity securities
Assets:
Available-for-sale Securities	6	6
Level 3
Assets:
Available-for-sale Securities	357	242
Asset derivatives	142	127
Other Investments	0	0
Cash and cash equivalents	0	0
Total assets	499	369
Liabilities:
Total liabilities	133	146
Level 3 | Foreign currency swaps
Assets:
Asset derivatives	140	125
Liabilities:
Liability derivatives	133	146
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	2
Level 3 | Fixed maturities
Assets:
Available-for-sale Securities	343	239
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	188	198
Level 3 | Fixed maturities | Public utilities
Assets:
Available-for-sale Securities	53	16
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	25
Level 3 | Fixed maturities | Other corporate
Assets:
Available-for-sale Securities	77	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	$ 14	$ 3