FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Assets:
Available for sale, fixed maturity securities	$ 103,128	$ 91,262
Equity securities	775	802
Other investments	823	628
Cash and cash equivalents	5,563	4,896
Asset derivatives	439	482
Total assets	110,728	98,070
Liabilities:
Liability derivatives	625	586
Total liabilities	625	586
Foreign currency swaps
Assets:
Asset derivatives	150	241
Liabilities:
Liability derivatives	289	204
Foreign currency forwards
Assets:
Asset derivatives	282	238
Liabilities:
Liability derivatives	335	377
Foreign currency options
Assets:
Asset derivatives	1
Liabilities:
Liability derivatives	1	5
Interest rate swaps
Assets:
Asset derivatives	6	3
Government and agencies
Assets:
Available for sale, fixed maturity securities	37,195	36,400
Municipalities
Assets:
Available for sale, fixed maturity securities	2,619	1,847
Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	717	410
Public utilities
Assets:
Available for sale, fixed maturity securities	10,398	6,780
Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	1,422	1,042
Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	11,696	10,287
Other corporate
Assets:
Available for sale, fixed maturity securities	39,081	34,496
Level 1
Assets:
Available for sale, fixed maturity securities	35,539	34,878
Equity securities	608	642
Other investments	823	628
Cash and cash equivalents	5,563	4,896
Asset derivatives	0	0
Total assets	42,533	41,044
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 \| Government and agencies
Assets:
Available for sale, fixed maturity securities	35,539	34,878
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	66,738	55,697
Equity securities	81	80
Other investments	0	0
Cash and cash equivalents	0	0
Asset derivatives	342	313
Total assets	67,161	56,090
Liabilities:
Total liabilities	385	460
Level 2 \| Foreign currency swaps
Assets:
Asset derivatives	53	72
Liabilities:
Liability derivatives	49	78
Level 2 \| Foreign currency forwards
Assets:
Asset derivatives	282	238
Liabilities:
Liability derivatives	335	377
Level 2 \| Foreign currency options
Assets:
Asset derivatives	1
Liabilities:
Liability derivatives	1	5
Level 2 \| Interest rate swaps
Assets:
Asset derivatives	6	3
Level 2 \| Government and agencies
Assets:
Available for sale, fixed maturity securities	1,656	1,522
Level 2 \| Municipalities
Assets:
Available for sale, fixed maturity securities	2,619	1,847
Level 2 \| Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	526	232
Level 2 \| Public utilities
Assets:
Available for sale, fixed maturity securities	10,030	6,556
Level 2 \| Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	1,422	1,042
Level 2 \| Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	11,672	10,264
Level 2 \| Other corporate
Assets:
Available for sale, fixed maturity securities	38,813	34,234
Level 3
Assets:
Available for sale, fixed maturity securities	851	687
Equity securities	86	80
Other investments	0	0
Cash and cash equivalents	0	0
Asset derivatives	97	169
Total assets	1,034	936
Liabilities:
Total liabilities	240	126
Level 3 \| Foreign currency swaps
Assets:
Asset derivatives	97	169
Liabilities:
Liability derivatives	240	126
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 \| 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	191	178
Level 3 \| Public utilities
Assets:
Available for sale, fixed maturity securities	368	224
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	$ 268	$ 262

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