COLLATERALIZED REINSURANCE, TRUST AGREEMENTS AND OTHER RESTRICTED ASSETS - Schedule of Premiums and Losses Ceded (Details) - Mt Logan Re - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023
Effects of Reinsurance [Line Items]
Ceded written premiums	$ 87	$ 53
Ceded earned premiums	87	46
Ceded losses and LAE	38	36
Assumed written premiums	1	1
Assumed earned premiums	1	1
Assumed losses and LAE	$ 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