REINSURANCE - Additional Information (Details) $ in Millions	Dec. 31, 2022 USD ($) counterparty	Dec. 31, 2021 USD ($) counterparty
Effects of Reinsurance [Line Items]
Funds withheld receivable at interest	$ 2,900.0	$ 3,000.0
Number of counterparties \| counterparty	6	6
Collateral held on behalf of reinsurers	$ 26,100.0	$ 23,400.0
Collateral held on our behalf by reinsurers	1,300.0	1,300.0
Reinsurer collateral, minimum amount held by trusts	65,800.0	55,200.0
Reinsurer collateral, reserves supported by trust assets	66,000.0	55,800.0
Cash Held In Trust
Effects of Reinsurance [Line Items]
Restricted cash	$ 31.3	$ 149.3

Amount of cash restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(1))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 8
-URI https://asc.fasb.org/extlink&oid=126999549&loc=SL98516268-108586

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(1)(a))
-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(2))
-URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910

Name:	us-gaap_RestrictedCash
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant