FAIR VALUE MEASUREMENTS - Changes in Investments and Derivatives Carried at Fair Value Classified as Level 3 (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 1,095	$ 695	$ 1,021	$ 810
Net investment gains (losses) included in earnings	(56)	23	(135)	(184)
Unrealized gains (losses) included in other comprehensive income (loss)	(14)	44	(42)	17
Purchases	109	39	283	155
Issuances	0	0	17	0
Sales	(8)	(5)	(31)	(6)
Settlements	(8)	(2)	(35)	(7)
Transfers into Level 3	0	0	55	24
Transfers out of Level 3	(44)	0	(59)	(15)
Balance, end of period	1,074	794	1,074	794
Change in unrealized gains (losses) still held	(72)	23	(178)	(184)
Foreign currency swaps
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning of period	(200)	(168)	(98)	43
Net investment gains (losses) included in earnings	(57)	23	(158)	(184)
Unrealized gains or losses included in other comprehensive income (loss)	0	2	(1)	(2)
Purchases	0	0	0	0
Issuances	0	0	0	0
Sales	0	0	0	0
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	(257)	(143)	(257)	(143)
Changes in unrealized gain (losses) still held	(57)	23	(158)	(184)
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	258	188	224	178
Net investment gains (losses) included in earnings	0	0	0	0
Unrealized gains (losses) included in other comprehensive income (loss)	(4)	3	(19)	5
Purchases	35	0	99	0
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	0	(1)
Transfers into Level 3	0	0	0	9
Transfers out of Level 3	(39)	0	(54)	0
Balance, end of period	250	191	250	191
Change in unrealized gains (losses) still held	(4)	0	(19)	0
Fixed maturity securities \| Public utilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	480	322	422	224
Net investment gains (losses) included in earnings	0	0	0	0
Unrealized gains (losses) included in other comprehensive income (loss)	(3)	15	(13)	6
Purchases	54	33	132	129
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	(8)	(2)	(18)	(6)
Transfers into Level 3	0	0	0	15
Transfers out of Level 3	0	0	0	0
Balance, end of period	523	368	523	368
Change in unrealized gains (losses) still held	(3)	0	(13)	0
Fixed maturity securities \| Sovereign and supranational
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	45		48
Net investment gains (losses) included in earnings	0		0
Unrealized gains (losses) included in other comprehensive income (loss)	0		(3)
Purchases	0		0
Issuances	0		0
Sales	0		(23)
Settlements	0		0
Transfers into Level 3	0		23
Transfers out of Level 3	0		0
Balance, end of period	45		45
Change in unrealized gains (losses) still held	0		(3)
Fixed maturity securities \| Banks/financial institutions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	38	24	24	23
Net investment gains (losses) included in earnings	0	0	0	0
Unrealized gains (losses) included in other comprehensive income (loss)	0	0	(1)	0
Purchases	8	0	23	1
Issuances	0	0	0	0
Sales	0	0	0	0
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	46	24	46	24
Change in unrealized gains (losses) still held	0	0	(1)	0
Fixed maturity securities \| Other corporate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	316	243	299	262
Net investment gains (losses) included in earnings	2	0	2	0
Unrealized gains (losses) included in other comprehensive income (loss)	(7)	24	(5)	8
Purchases	0	1	0	13
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	(17)	0
Transfers into Level 3	0	0	32	0
Transfers out of Level 3	(5)	0	(5)	(15)
Balance, end of period	306	268	306	268
Change in unrealized gains (losses) still held	(7)	0	(5)	0
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	158	86	102	80
Net investment gains (losses) included in earnings	(1)	0	21	0
Unrealized gains (losses) included in other comprehensive income (loss)	0	0	0	0
Purchases	12	5	29	12
Issuances	0	0	17	0
Sales	(8)	(5)	(8)	(6)
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	161	86	161	86
Change in unrealized gains (losses) still held	$ (1)	$ 0	$ 21	$ 0

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

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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 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 transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy.

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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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Amount of unrealized gain (loss) recognized in income for derivative asset (liability) after deduction of derivative liability (asset), measured at fair value using unobservable input (level 3) and still held.

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Amount of gain (loss) recognized in income from derivative asset (liability) after deduction of derivative liability (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 from derivative asset (liability) after deduction of derivative liability (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 a derivative asset (liability) after deduction of derivative liability (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 a derivative asset (liability) after deduction of derivative liability (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 sales of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (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 settlements of financial instrument classified as a derivative asset (liability) after deduction of derivative liability, 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 a derivative asset (liability) after deduction of derivative liability (asset) into level 3 of the fair value hierarchy.

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Amount of transfers of financial instrument classified as derivative asset (liability) after deduction of derivative liability (asset) out of level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as derivative asset (liability) after deduction of derivative liability (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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