FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Assets:
Available-for-sale Securities	$ 83,206	$ 76,702
Asset derivatives	479	1,207
Other Investments	57	276
Cash and cash equivalents	4,927	4,859
Total assets	88,669	83,044
Liabilities:
Liability derivatives	974	1,998
Total liabilities	974	1,998
Foreign currency swaps
Assets:
Asset derivatives	301	490
Liabilities:
Liability derivatives	196	230
Foreign currency forwards
Assets:
Asset derivatives	160	672
Liabilities:
Liability derivatives	754	1,717
Foreign currency options
Assets:
Asset derivatives	17	43
Liabilities:
Liability derivatives	24	51
Credit default swaps
Assets:
Asset derivatives	1	2
Fixed maturities
Assets:
Available-for-sale Securities	80,415	73,760
Fixed maturities | Government and agencies
Assets:
Available-for-sale Securities	30,038	26,214
Fixed maturities | Municipalities
Assets:
Available-for-sale Securities	1,292	1,295
Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale Securities	456	1,337
Fixed maturities | Public utilities
Assets:
Available-for-sale Securities	8,015	7,683
Fixed maturities | Sovereign and supranational
Assets:
Available-for-sale Securities	2,029	1,469
Fixed maturities | Banks/financial institutions
Assets:
Available-for-sale Securities	7,010	6,063
Fixed maturities | Other corporate
Assets:
Available-for-sale Securities	31,575	29,699
Perpetual securities
Assets:
Available-for-sale Securities	1,863	1,633
Perpetual securities | Banks/financial institutions
Assets:
Available-for-sale Securities	1,627	1,420
Perpetual securities | Other corporate
Assets:
Available-for-sale Securities	236	213
Equity securities
Assets:
Available-for-sale Securities	928	1,309
Level 1
Assets:
Available-for-sale Securities	29,972	26,687
Asset derivatives	0	0
Other Investments	57	276
Cash and cash equivalents	4,927	4,859
Total assets	34,956	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	29,067	25,387
Level 1 | Fixed maturities | Government and agencies
Assets:
Available-for-sale Securities	29,067	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	905	1,300
Level 2
Assets:
Available-for-sale Securities	52,834	49,773
Asset derivatives	331	1,080
Other Investments	0	0
Cash and cash equivalents	0	0
Total assets	53,165	50,853
Liabilities:
Total liabilities	842	1,852
Level 2 | Foreign currency swaps
Assets:
Asset derivatives	154	365
Liabilities:
Liability derivatives	64	84
Level 2 | Foreign currency forwards
Assets:
Asset derivatives	160	672
Liabilities:
Liability derivatives	754	1,717
Level 2 | Foreign currency options
Assets:
Asset derivatives	17	43
Liabilities:
Liability derivatives	24	51
Level 2 | Credit default swaps
Assets:
Asset derivatives	0	0
Level 2 | Fixed maturities
Assets:
Available-for-sale Securities	50,966	48,134
Level 2 | Fixed maturities | Government and agencies
Assets:
Available-for-sale Securities	971	827
Level 2 | Fixed maturities | Municipalities
Assets:
Available-for-sale Securities	1,292	1,295
Level 2 | Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale Securities	278	1,139
Level 2 | Fixed maturities | Public utilities
Assets:
Available-for-sale Securities	7,938	7,667
Level 2 | Fixed maturities | Sovereign and supranational
Assets:
Available-for-sale Securities	2,029	1,469
Level 2 | Fixed maturities | Banks/financial institutions
Assets:
Available-for-sale Securities	6,985	6,038
Level 2 | Fixed maturities | Other corporate
Assets:
Available-for-sale Securities	31,473	29,699
Level 2 | Perpetual securities
Assets:
Available-for-sale Securities	1,863	1,633
Level 2 | Perpetual securities | Banks/financial institutions
Assets:
Available-for-sale Securities	1,627	1,420
Level 2 | Perpetual securities | Other corporate
Assets:
Available-for-sale Securities	236	213
Level 2 | Equity securities
Assets:
Available-for-sale Securities	5	6
Level 3
Assets:
Available-for-sale Securities	400	242
Asset derivatives	148	127
Other Investments	0	0
Cash and cash equivalents	0	0
Total assets	548	369
Liabilities:
Total liabilities	132	146
Level 3 | Foreign currency swaps
Assets:
Asset derivatives	147	125
Liabilities:
Liability derivatives	132	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	1	2
Level 3 | Fixed maturities
Assets:
Available-for-sale Securities	382	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	178	198
Level 3 | Fixed maturities | Public utilities
Assets:
Available-for-sale Securities	77	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	102	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	$ 18	$ 3