REINSURANCE - Effect of Reinsurance on Premiums and Benefits and Claims (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Reinsurance Disclosures [Abstract]
Earned premiums, direct		$ 3,413	$ 3,360	$ 10,371	$ 10,194
Earned premiums, ceded		(92)	(71)	(271)	(206)
Earned premiums, assumed		51	39	123	121
Net earned premiums	[1]	3,372	3,328	10,223	10,109
Benefits and claims, excluding reserve remeasurement, direct		2,051	2,024	6,179	6,101
Benefits and claims, excluding reserve remeasurement, ceded		(57)	(36)	(177)	(104)
Benefits and claims, excluding reserve remeasurement, assumed		22	15	47	45
Benefits and claims, excluding reserve remeasurement		2,016	2,003	6,049	6,042
Reserve remeasurement (gains) losses, direct		(570)	(407)	(648)	(515)
Reserve remeasurement (gains) losses, ceded		(10)	(1)	(10)	0
Reserve remeasurement (gains) losses		(580)	(408)	(658)	(515)
Total benefits and claims, net		$ 1,436	$ 1,595	$ 5,391	$ 5,527

[1] Includes a gain (loss) of $(55) and $(75) for the three-month periods and $(55) and $(80) for the nine-month periods ended September 30, 2025 and 2024, respectively, related to remeasurement of the deferred profit liability for limited-payment contracts.