FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Assets:
Fixed maturity securities, available-for-sale	$ 67,276	$ 65,269
Equity securities	885	796
Other investments	2,346	1,599
Cash and cash equivalents	6,768	6,229
Asset derivatives	107	240
Total assets	77,382	74,133
Liabilities:
Liability derivatives	934	933
Total liabilities	934	933
Foreign currency swaps
Assets:
Asset derivatives	44	55
Liabilities:
Liability derivatives	685	604
Foreign currency forwards
Assets:
Asset derivatives	46	185
Liabilities:
Liability derivatives	18
Foreign currency options
Assets:
Asset derivatives	1
Interest rate swaps
Assets:
Asset derivatives	16
Liabilities:
Liability derivatives	231	329
Government and agencies
Assets:
Fixed maturity securities, available-for-sale	16,583	17,846
Municipalities
Assets:
Fixed maturity securities, available-for-sale	1,986	2,034
Mortgage- and asset-backed securities
Assets:
Fixed maturity securities, available-for-sale	4,362	3,563
Public utilities
Assets:
Fixed maturity securities, available-for-sale	7,430	7,045
Sovereign and supranational
Assets:
Fixed maturity securities, available-for-sale	425	416
Banks/financial institutions
Assets:
Fixed maturity securities, available-for-sale	9,719	8,956
Other corporate
Assets:
Fixed maturity securities, available-for-sale	26,771	25,409
Level 1
Assets:
Fixed maturity securities, available-for-sale	15,854	17,088
Equity securities	722	639
Other investments	2,346	1,599
Cash and cash equivalents	6,768	6,229
Asset derivatives	0	0
Total assets	25,690	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	15,854	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	48,176	46,114
Equity securities	0	0
Other investments	0	0
Cash and cash equivalents	0	0
Asset derivatives	107	240
Total assets	48,283	46,354
Liabilities:
Total liabilities	934	933
Level 2 | Foreign currency swaps
Assets:
Asset derivatives	44	55
Liabilities:
Liability derivatives	685	604
Level 2 | Foreign currency forwards
Assets:
Asset derivatives	46	185
Liabilities:
Liability derivatives	18
Level 2 | Foreign currency options
Assets:
Asset derivatives	1
Level 2 | Interest rate swaps
Assets:
Asset derivatives	16
Liabilities:
Liability derivatives	231	329
Level 2 | Government and agencies
Assets:
Fixed maturity securities, available-for-sale	729	758
Level 2 | Municipalities
Assets:
Fixed maturity securities, available-for-sale	1,986	2,034
Level 2 | Mortgage- and asset-backed securities
Assets:
Fixed maturity securities, available-for-sale	2,116	2,407
Level 2 | Public utilities
Assets:
Fixed maturity securities, available-for-sale	6,624	6,398
Level 2 | Sovereign and supranational
Assets:
Fixed maturity securities, available-for-sale	403	393
Level 2 | Banks/financial institutions
Assets:
Fixed maturity securities, available-for-sale	9,710	8,946
Level 2 | Other corporate
Assets:
Fixed maturity securities, available-for-sale	26,608	25,178
Level 3
Assets:
Fixed maturity securities, available-for-sale	3,246	2,067
Equity securities	163	157
Other investments	0	0
Cash and cash equivalents	0	0
Asset derivatives	0	0
Total assets	3,409	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	2,246	1,156
Level 3 | Public utilities
Assets:
Fixed maturity securities, available-for-sale	806	647
Level 3 | Sovereign and supranational
Assets:
Fixed maturity securities, available-for-sale	22	23
Level 3 | Banks/financial institutions
Assets:
Fixed maturity securities, available-for-sale	9	10
Level 3 | Other corporate
Assets:
Fixed maturity securities, available-for-sale	$ 163	$ 231