FAIR VALUE MEASUREMENTS - Changes in Investments Carried at Fair Value Classified as Level 3 (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 3,919	$ 3,076	$ 3,517	$ 2,224
Net investment gains (losses) included in earnings	6	(4)	28	0
Unrealized gains (losses) included in other comprehensive income (loss)	(141)	14	(221)	69
Purchases	482	218	1,023	1,016
Issuances	0	0	0	0
Sales	0	(1)	0	(2)
Settlements	(99)	(69)	(348)	(161)
Transfers into Level 3	386	175	645	358
Transfers out of Level 3	0	0	(91)	(95)
Balance, end of period	4,553	3,409	4,553	3,409
Changes in unrealized gains (losses) relating to Level 3 assets and liabilities still held at the end of the period included in earnings	$ 4	$ 0	$ 8	$ 4
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net investment gains (losses)	Net investment gains (losses)	Net investment gains (losses)	Net investment gains (losses)
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Asset, Gain (Loss), Statement of Other Comprehensive Income or Comprehensive Income [Extensible Enumeration]	Other Comprehensive Income (Loss), before Tax	Other Comprehensive Income (Loss), before Tax	Other Comprehensive Income (Loss), before Tax	Other Comprehensive Income (Loss), before Tax
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net investment gains (losses), Other Comprehensive Income (Loss), before Tax	Net investment gains (losses), Other Comprehensive Income (Loss), before Tax	Net investment gains (losses), Other Comprehensive Income (Loss), before Tax	Net investment gains (losses), Other Comprehensive Income (Loss), before Tax
Fixed maturity securities \| Mortgage- and asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 2,753	$ 1,922	$ 2,294	$ 1,156
Net investment gains (losses) included in earnings	3	0	17	0
Unrealized gains (losses) included in other comprehensive income (loss)	(81)	6	(129)	36
Purchases	436	208	927	817
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	(87)	(65)	(258)	(121)
Transfers into Level 3	386	175	645	358
Transfers out of Level 3	0	0	(86)	0
Balance, end of period	3,410	2,246	3,410	2,246
Changes in unrealized gains (losses) relating to Level 3 assets and liabilities still held at the end of the period included in earnings	2	0	4	0
Fixed maturity securities \| Public utilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	852	792	876	647
Net investment gains (losses) included in earnings	0	0	5	0
Unrealized gains (losses) included in other comprehensive income (loss)	(54)	9	(78)	29
Purchases	30	9	79	167
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	(6)	(4)	(60)	(37)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	822	806	822	806
Changes in unrealized gains (losses) relating to Level 3 assets and liabilities still held at the end of the period included in earnings	0	0	1	0
Fixed maturity securities \| Sovereign and supranational
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	17	23	19	23
Net investment gains (losses) included in earnings	0	0	0	0
Unrealized gains (losses) included in other comprehensive income (loss)	0	(1)	0	1
Purchases	0	0	0	0
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	(2)	(2)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	17	22	17	22
Changes in unrealized gains (losses) relating to Level 3 assets and liabilities still held at the end of the period included in earnings	0	0	0	0
Fixed maturity securities \| Banks/financial institutions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	4	9	9	10
Net investment gains (losses) included in earnings	1	0	1	0
Unrealized gains (losses) included in other comprehensive income (loss)	0	0	0	(1)
Purchases	0	0	0	0
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	(5)	0	(5)	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	(5)	0
Balance, end of period	0	9	0	9
Changes in unrealized gains (losses) relating to Level 3 assets and liabilities still held at the end of the period included in earnings	0	0	0	0
Fixed maturity securities \| Other corporate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	135	163	159	231
Net investment gains (losses) included in earnings	0	0	6	0
Unrealized gains (losses) included in other comprehensive income (loss)	(6)	0	(14)	4
Purchases	0	0	0	24
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	(1)	0	(23)	(1)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	(95)
Balance, end of period	128	163	128	163
Changes in unrealized gains (losses) relating to Level 3 assets and liabilities still held at the end of the period included in earnings	0	0	0	0
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	158	167	160	157
Net investment gains (losses) included in earnings	2	(4)	(1)	0
Unrealized gains (losses) included in other comprehensive income (loss)	0	0	0	0
Purchases	16	1	17	8
Issuances	0	0	0	0
Sales	0	(1)	0	(2)
Settlements	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	176	163	176	163
Changes in unrealized gains (losses) relating to Level 3 assets and liabilities still held at the end of the period included in earnings	$ 2	$ 0	$ 3	$ 4

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Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

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Amount of gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3).

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Amount of issuances of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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