FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Assets:
Available for sale, fixed maturity securities	$ 99,959	$ 91,262
Equity securities	749	802
Other investments	763	628
Cash and cash equivalents	5,528	4,896
Asset derivatives	474	482
Total assets	107,473	98,070
Liabilities:
Liability derivatives	680	586
Total liabilities	680	586
Foreign currency swaps
Assets:
Asset derivatives	160	241
Liabilities:
Liability derivatives	284	204
Foreign currency forwards
Assets:
Asset derivatives	299	238
Liabilities:
Liability derivatives	393	377
Foreign currency options
Assets:
Asset derivatives	1
Liabilities:
Liability derivatives	2	5
Interest rate swaps
Assets:
Asset derivatives	14	3
Forward bond purchase commitment
Liabilities:
Liability derivatives	1
Government and agencies
Assets:
Available for sale, fixed maturity securities	36,487	36,400
Municipalities
Assets:
Available for sale, fixed maturity securities	2,492	1,847
Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	546	410
Public utilities
Assets:
Available for sale, fixed maturity securities	9,942	6,780
Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	1,377	1,042
Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	11,214	10,287
Other corporate
Assets:
Available for sale, fixed maturity securities	37,901	34,496
Level 1
Assets:
Available for sale, fixed maturity securities	34,980	34,878
Equity securities	587	642
Other investments	763	628
Cash and cash equivalents	5,528	4,896
Asset derivatives	0	0
Total assets	41,858	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 | Forward bond purchase commitment
Liabilities:
Liability derivatives	0
Level 1 | Government and agencies
Assets:
Available for sale, fixed maturity securities	34,980	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	64,202	55,697
Equity securities	76	80
Other investments	0	0
Cash and cash equivalents	0	0
Asset derivatives	387	313
Total assets	64,665	56,090
Liabilities:
Total liabilities	425	460
Level 2 | Foreign currency swaps
Assets:
Asset derivatives	73	72
Liabilities:
Liability derivatives	29	78
Level 2 | Foreign currency forwards
Assets:
Asset derivatives	299	238
Liabilities:
Liability derivatives	393	377
Level 2 | Foreign currency options
Assets:
Asset derivatives	1
Liabilities:
Liability derivatives	2	5
Level 2 | Interest rate swaps
Assets:
Asset derivatives	14	3
Level 2 | Forward bond purchase commitment
Liabilities:
Liability derivatives	1
Level 2 | Government and agencies
Assets:
Available for sale, fixed maturity securities	1,507	1,522
Level 2 | Municipalities
Assets:
Available for sale, fixed maturity securities	2,492	1,847
Level 2 | Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	358	232
Level 2 | Public utilities
Assets:
Available for sale, fixed maturity securities	9,620	6,556
Level 2 | Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	1,377	1,042
Level 2 | Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	11,190	10,264
Level 2 | Other corporate
Assets:
Available for sale, fixed maturity securities	37,658	34,234
Level 3
Assets:
Available for sale, fixed maturity securities	777	687
Equity securities	86	80
Other investments	0	0
Cash and cash equivalents	0	0
Asset derivatives	87	169
Total assets	950	936
Liabilities:
Total liabilities	255	126
Level 3 | Foreign currency swaps
Assets:
Asset derivatives	87	169
Liabilities:
Liability derivatives	255	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 | Forward bond purchase commitment
Liabilities:
Liability derivatives	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	188	178
Level 3 | Public utilities
Assets:
Available for sale, fixed maturity securities	322	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	$ 243	$ 262