FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Assets:
Available for sale, fixed maturity securities	$ 92,435	$ 82,895
Equity securities	1,087	987
Other investments	677	152
Cash and cash equivalents	3,019	4,337
Asset derivatives	526	417
Total assets	97,744	88,788
Liabilities:
Liability derivatives	347	387
Total liabilities	347	387
Foreign currency swaps
Assets:
Asset derivatives	289	285
Liabilities:
Liability derivatives	214	234
Foreign currency forwards
Assets:
Asset derivatives	222	126
Liabilities:
Liability derivatives	128	151
Foreign currency options
Assets:
Asset derivatives		3
Liabilities:
Liability derivatives	2	1
Interest rate swaps
Assets:
Asset derivatives	15	3
Interest rate swaptions
Liabilities:
Liability derivatives	3	1
Government and agencies
Assets:
Available for sale, fixed maturity securities	38,160	34,342
Municipalities
Assets:
Available for sale, fixed maturity securities	1,975	1,863
Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	416	339
Public utilities
Assets:
Available for sale, fixed maturity securities	6,805	7,171
Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	1,152	1,260
Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	10,152	8,918
Other corporate
Assets:
Available for sale, fixed maturity securities	33,775	29,002
Level 1
Assets:
Available for sale, fixed maturity securities	36,573	32,993
Equity securities	949	874
Other investments	677	152
Cash and cash equivalents	3,019	4,337
Asset derivatives	0	0
Total assets	41,218	38,356
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
Liabilities:
Liability derivatives	0	0
Level 1 \| Interest rate swaps
Assets:
Asset derivatives	0	0
Level 1 \| Interest rate swaptions
Liabilities:
Liability derivatives	0	0
Level 1 \| Government and agencies
Assets:
Available for sale, fixed maturity securities	36,573	32,993
Level 1 \| Municipalities
Assets:
Available for sale, fixed maturity securities	0	0
Level 1 \| Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	0	0
Level 1 \| Public utilities
Assets:
Available for sale, fixed maturity securities	0	0
Level 1 \| Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	0	0
Level 1 \| Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	0	0
Level 1 \| Other corporate
Assets:
Available for sale, fixed maturity securities	0	0
Level 2
Assets:
Available for sale, fixed maturity securities	55,252	49,380
Equity securities	73	67
Other investments	0	0
Cash and cash equivalents	0	0
Asset derivatives	325	235
Total assets	55,650	49,682
Liabilities:
Total liabilities	240	285
Level 2 \| Foreign currency swaps
Assets:
Asset derivatives	88	103
Liabilities:
Liability derivatives	107	132
Level 2 \| Foreign currency forwards
Assets:
Asset derivatives	222	126
Liabilities:
Liability derivatives	128	151
Level 2 \| Foreign currency options
Assets:
Asset derivatives		3
Liabilities:
Liability derivatives	2	1
Level 2 \| Interest rate swaps
Assets:
Asset derivatives	15	3
Level 2 \| Interest rate swaptions
Liabilities:
Liability derivatives	3	1
Level 2 \| Government and agencies
Assets:
Available for sale, fixed maturity securities	1,587	1,349
Level 2 \| Municipalities
Assets:
Available for sale, fixed maturity securities	1,975	1,863
Level 2 \| Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	233	162
Level 2 \| Public utilities
Assets:
Available for sale, fixed maturity securities	6,601	7,062
Level 2 \| Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	1,152	1,260
Level 2 \| Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	10,128	8,895
Level 2 \| Other corporate
Assets:
Available for sale, fixed maturity securities	33,576	28,789
Level 3
Assets:
Available for sale, fixed maturity securities	610	522
Equity securities	65	46
Other investments	0	0
Cash and cash equivalents	0	0
Asset derivatives	201	182
Total assets	876	750
Liabilities:
Total liabilities	107	102
Level 3 \| Foreign currency swaps
Assets:
Asset derivatives	201	182
Liabilities:
Liability derivatives	107	102
Level 3 \| Foreign currency forwards
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	0	0
Level 3 \| Foreign currency options
Assets:
Asset derivatives		0
Liabilities:
Liability derivatives	0	0
Level 3 \| Interest rate swaps
Assets:
Asset derivatives	0	0
Level 3 \| Interest rate swaptions
Liabilities:
Liability derivatives	0	0
Level 3 \| Government and agencies
Assets:
Available for sale, fixed maturity securities	0	0
Level 3 \| Municipalities
Assets:
Available for sale, fixed maturity securities	0	0
Level 3 \| Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	183	177
Level 3 \| Public utilities
Assets:
Available for sale, fixed maturity securities	204	109
Level 3 \| Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	0	0
Level 3 \| Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	24	23
Level 3 \| Other corporate
Assets:
Available for sale, fixed maturity securities	$ 199	$ 213

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