FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Assets:
Available for sale, fixed maturity securities	$ 78,099	$ 75,741
Equity securities	1,087	1,091
Other investments	2,561	1,532
Cash and cash equivalents	3,809	3,943
Asset derivatives	549	617
Total assets	86,105	82,924
Liabilities:
Liability derivatives	1,058	1,698
Total liabilities	1,058	1,698
Foreign currency swaps
Assets:
Asset derivatives	118	128
Liabilities:
Liability derivatives	399	390
Foreign currency forwards
Assets:
Asset derivatives	359	400
Liabilities:
Liability derivatives	176	725
Foreign currency options
Assets:
Asset derivatives	46	82
Interest rate swaps
Assets:
Asset derivatives	26	7
Liabilities:
Liability derivatives	483	583
Government and agencies
Assets:
Available for sale, fixed maturity securities	25,893	25,114
Municipalities
Assets:
Available for sale, fixed maturity securities	2,416	2,320
Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	2,567	2,146
Public utilities
Assets:
Available for sale, fixed maturity securities	7,933	7,666
Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	728	834
Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	9,420	9,299
Other corporate
Assets:
Available for sale, fixed maturity securities	29,142	28,362
Level 1
Assets:
Available for sale, fixed maturity securities	24,903	24,158
Equity securities	806	822
Other investments	2,561	1,532
Cash and cash equivalents	3,809	3,943
Asset derivatives	0	0
Total assets	32,079	30,455
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
Level 1 \| Interest rate swaps
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	0	0
Level 1 \| Government and agencies
Assets:
Available for sale, fixed maturity securities	24,903	24,158
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	51,477	49,805
Equity securities	60	60
Other investments	0	0
Cash and cash equivalents	0	0
Asset derivatives	549	617
Total assets	52,086	50,482
Liabilities:
Total liabilities	1,058	1,698
Level 2 \| Foreign currency swaps
Assets:
Asset derivatives	118	128
Liabilities:
Liability derivatives	399	390
Level 2 \| Foreign currency forwards
Assets:
Asset derivatives	359	400
Liabilities:
Liability derivatives	176	725
Level 2 \| Foreign currency options
Assets:
Asset derivatives	46	82
Level 2 \| Interest rate swaps
Assets:
Asset derivatives	26	7
Liabilities:
Liability derivatives	483	583
Level 2 \| Government and agencies
Assets:
Available for sale, fixed maturity securities	990	956
Level 2 \| Municipalities
Assets:
Available for sale, fixed maturity securities	2,416	2,320
Level 2 \| Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	2,149	1,803
Level 2 \| Public utilities
Assets:
Available for sale, fixed maturity securities	7,583	7,169
Level 2 \| Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	691	797
Level 2 \| Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	9,259	9,140
Level 2 \| Other corporate
Assets:
Available for sale, fixed maturity securities	28,389	27,620
Level 3
Assets:
Available for sale, fixed maturity securities	1,719	1,778
Equity securities	221	209
Other investments	0	0
Cash and cash equivalents	0	0
Asset derivatives	0	0
Total assets	1,940	1,987
Liabilities:
Total liabilities	0	0
Level 3 \| Foreign currency swaps
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	0	0
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
Level 3 \| Interest rate swaps
Assets:
Asset derivatives	0	0
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	418	343
Level 3 \| Public utilities
Assets:
Available for sale, fixed maturity securities	350	497
Level 3 \| Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	37	37
Level 3 \| Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	161	159
Level 3 \| Other corporate
Assets:
Available for sale, fixed maturity securities	$ 753	$ 742

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