FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Assets:
Available-for-sale Securities	$ 80,196	$ 76,702
Asset derivatives	580	1,207
Other Investments	141	276
Cash and cash equivalents	4,205	4,859
Total assets	85,122	83,044
Liabilities:
Liability derivatives	1,099	1,998
Total liabilities	1,099	1,998
Foreign currency swaps
Assets:
Asset derivatives	318	490
Liabilities:
Liability derivatives	224	230
Foreign currency forwards
Assets:
Asset derivatives	235	672
Liabilities:
Liability derivatives	853	1,717
Foreign currency options
Assets:
Asset derivatives	25	43
Liabilities:
Liability derivatives	22	51
Credit default swaps
Assets:
Asset derivatives	2	2
Fixed maturities
Assets:
Available-for-sale Securities	77,077	73,760
Fixed maturities | Government and agencies
Assets:
Available-for-sale Securities	29,320	26,214
Fixed maturities | Municipalities
Assets:
Available-for-sale Securities	1,322	1,295
Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale Securities	504	1,337
Fixed maturities | Public utilities
Assets:
Available-for-sale Securities	7,843	7,683
Fixed maturities | Sovereign and supranational
Assets:
Available-for-sale Securities	1,386	1,469
Fixed maturities | Banks/financial institutions
Assets:
Available-for-sale Securities	6,545	6,063
Fixed maturities | Other corporate
Assets:
Available-for-sale Securities	30,157	29,699
Perpetual securities
Assets:
Available-for-sale Securities	1,770	1,633
Perpetual securities | Banks/financial institutions
Assets:
Available-for-sale Securities	1,551	1,420
Perpetual securities | Other corporate
Assets:
Available-for-sale Securities	219	213
Equity securities
Assets:
Available-for-sale Securities	1,349	1,309
Level 1
Assets:
Available-for-sale Securities	29,796	26,687
Asset derivatives	0	0
Other Investments	141	276
Cash and cash equivalents	4,205	4,859
Total assets	34,142	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	28,457	25,387
Level 1 | Fixed maturities | Government and agencies
Assets:
Available-for-sale Securities	28,457	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	1,339	1,300
Level 2
Assets:
Available-for-sale Securities	50,126	49,773
Asset derivatives	434	1,080
Other Investments	0	0
Cash and cash equivalents	0	0
Total assets	50,560	50,853
Liabilities:
Total liabilities	974	1,852
Level 2 | Foreign currency swaps
Assets:
Asset derivatives	174	365
Liabilities:
Liability derivatives	99	84
Level 2 | Foreign currency forwards
Assets:
Asset derivatives	235	672
Liabilities:
Liability derivatives	853	1,717
Level 2 | Foreign currency options
Assets:
Asset derivatives	25	43
Liabilities:
Liability derivatives	22	51
Level 2 | Credit default swaps
Assets:
Asset derivatives	0	0
Level 2 | Fixed maturities
Assets:
Available-for-sale Securities	48,350	48,134
Level 2 | Fixed maturities | Government and agencies
Assets:
Available-for-sale Securities	863	827
Level 2 | Fixed maturities | Municipalities
Assets:
Available-for-sale Securities	1,322	1,295
Level 2 | Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available-for-sale Securities	309	1,139
Level 2 | Fixed maturities | Public utilities
Assets:
Available-for-sale Securities	7,827	7,667
Level 2 | Fixed maturities | Sovereign and supranational
Assets:
Available-for-sale Securities	1,386	1,469
Level 2 | Fixed maturities | Banks/financial institutions
Assets:
Available-for-sale Securities	6,521	6,038
Level 2 | Fixed maturities | Other corporate
Assets:
Available-for-sale Securities	30,122	29,699
Level 2 | Perpetual securities
Assets:
Available-for-sale Securities	1,770	1,633
Level 2 | Perpetual securities | Banks/financial institutions
Assets:
Available-for-sale Securities	1,551	1,420
Level 2 | Perpetual securities | Other corporate
Assets:
Available-for-sale Securities	219	213
Level 2 | Equity securities
Assets:
Available-for-sale Securities	6	6
Level 3
Assets:
Available-for-sale Securities	274	242
Asset derivatives	146	127
Other Investments	0	0
Cash and cash equivalents	0	0
Total assets	420	369
Liabilities:
Total liabilities	125	146
Level 3 | Foreign currency swaps
Assets:
Asset derivatives	144	125
Liabilities:
Liability derivatives	125	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	270	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	195	198
Level 3 | Fixed maturities | Public utilities
Assets:
Available-for-sale Securities	16	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	24	25
Level 3 | Fixed maturities | Other corporate
Assets:
Available-for-sale Securities	35	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	$ 4	$ 3