FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Assets:
Fixed maturity securities, available-for-sale	$ 67,144	$ 65,269
Equity securities	764	796
Other investments	2,259	1,599
Cash and cash equivalents	5,231	6,229
Asset derivatives	148	240
Total assets	75,546	74,133
Liabilities:
Liability derivatives	985	933
Total liabilities	985	933
Foreign currency swaps
Assets:
Asset derivatives	49	55
Liabilities:
Liability derivatives	642	604
Foreign currency forwards
Assets:
Asset derivatives	92	185
Liabilities:
Liability derivatives	39
Foreign currency options
Assets:
Asset derivatives	2
Interest rate swaps
Assets:
Asset derivatives	5
Liabilities:
Liability derivatives	304	329
Government and agencies
Assets:
Fixed maturity securities, available-for-sale	17,817	17,846
Municipalities
Assets:
Fixed maturity securities, available-for-sale	2,055	2,034
Mortgage- and asset-backed securities
Assets:
Fixed maturity securities, available-for-sale	4,048	3,563
Public utilities
Assets:
Fixed maturity securities, available-for-sale	7,221	7,045
Sovereign and supranational
Assets:
Fixed maturity securities, available-for-sale	426	416
Banks/financial institutions
Assets:
Fixed maturity securities, available-for-sale	9,361	8,956
Other corporate
Assets:
Fixed maturity securities, available-for-sale	26,216	25,409
Level 1
Assets:
Fixed maturity securities, available-for-sale	16,972	17,088
Equity securities	604	639
Other investments	2,259	1,599
Cash and cash equivalents	5,231	6,229
Asset derivatives	0	0
Total assets	25,066	25,555
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
Level 1 | Foreign currency options
Assets:
Asset derivatives	0
Level 1 | Interest rate swaps
Assets:
Asset derivatives	0
Liabilities:
Liability derivatives	0	0
Level 1 | Government and agencies
Assets:
Fixed maturity securities, available-for-sale	16,972	17,088
Level 1 | Municipalities
Assets:
Fixed maturity securities, available-for-sale	0	0
Level 1 | Mortgage- and asset-backed securities
Assets:
Fixed maturity securities, available-for-sale	0	0
Level 1 | Public utilities
Assets:
Fixed maturity securities, available-for-sale	0	0
Level 1 | Sovereign and supranational
Assets:
Fixed maturity securities, available-for-sale	0	0
Level 1 | Banks/financial institutions
Assets:
Fixed maturity securities, available-for-sale	0	0
Level 1 | Other corporate
Assets:
Fixed maturity securities, available-for-sale	0	0
Level 2
Assets:
Fixed maturity securities, available-for-sale	47,642	46,114
Equity securities	0	0
Other investments	0	0
Cash and cash equivalents	0	0
Asset derivatives	148	240
Total assets	47,790	46,354
Liabilities:
Total liabilities	985	933
Level 2 | Foreign currency swaps
Assets:
Asset derivatives	49	55
Liabilities:
Liability derivatives	642	604
Level 2 | Foreign currency forwards
Assets:
Asset derivatives	92	185
Liabilities:
Liability derivatives	39
Level 2 | Foreign currency options
Assets:
Asset derivatives	2
Level 2 | Interest rate swaps
Assets:
Asset derivatives	5
Liabilities:
Liability derivatives	304	329
Level 2 | Government and agencies
Assets:
Fixed maturity securities, available-for-sale	845	758
Level 2 | Municipalities
Assets:
Fixed maturity securities, available-for-sale	2,055	2,034
Level 2 | Mortgage- and asset-backed securities
Assets:
Fixed maturity securities, available-for-sale	2,445	2,407
Level 2 | Public utilities
Assets:
Fixed maturity securities, available-for-sale	6,465	6,398
Level 2 | Sovereign and supranational
Assets:
Fixed maturity securities, available-for-sale	402	393
Level 2 | Banks/financial institutions
Assets:
Fixed maturity securities, available-for-sale	9,351	8,946
Level 2 | Other corporate
Assets:
Fixed maturity securities, available-for-sale	26,079	25,178
Level 3
Assets:
Fixed maturity securities, available-for-sale	2,530	2,067
Equity securities	160	157
Other investments	0	0
Cash and cash equivalents	0	0
Asset derivatives	0	0
Total assets	2,690	2,224
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
Level 3 | Foreign currency options
Assets:
Asset derivatives	0
Level 3 | Interest rate swaps
Assets:
Asset derivatives	0
Liabilities:
Liability derivatives	0	0
Level 3 | Government and agencies
Assets:
Fixed maturity securities, available-for-sale	0	0
Level 3 | Municipalities
Assets:
Fixed maturity securities, available-for-sale	0	0
Level 3 | Mortgage- and asset-backed securities
Assets:
Fixed maturity securities, available-for-sale	1,603	1,156
Level 3 | Public utilities
Assets:
Fixed maturity securities, available-for-sale	756	647
Level 3 | Sovereign and supranational
Assets:
Fixed maturity securities, available-for-sale	24	23
Level 3 | Banks/financial institutions
Assets:
Fixed maturity securities, available-for-sale	10	10
Level 3 | Other corporate
Assets:
Fixed maturity securities, available-for-sale	$ 137	$ 231