COLLATERALIZED REINSURANCE AND TRUST AGREEMENTS - Premiums and Losses Ceded to Affiliate (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Collateralized Reinsurance And Trust Agreements [Abstract]
Ceded written premiums	$ 89	$ 68	$ 187	$ 150
Ceded earned premiums	74	57	172	149
Ceded losses and LAE	26	99	79	161
Assumed written premiums	2	2	3	3
Assumed earned premiums	2	2	3	3
Assumed losses and LAE	$ 0	$ 0	$ 0	$ 0

Amount of written premiums ceded to other entities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 944
-SubTopic 605
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479655/944-605-50-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 944
-SubTopic 605
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479655/944-605-50-1

Name:	us-gaap_CededPremiumsWritten
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration