Recent Acquisitions, Disposals & Other Transactions - Schedule of Merger Identifiable Assets and Liabilities (Details) - Argo Group International Holdings, Inc. - Brookfield Wealth Solutions - USD ($) $ in Millions			2 Months Ended
	Nov. 16, 2023	Nov. 15, 2023	Dec. 31, 2023
Business Acquisition [Line Items]
Number of common stock shares canceled (in shares)		35,221,291	35,221,291
Consideration transferred	$ 1,058.9
Assets
Fixed maturities available-for-sale, at fair value	2,525.3
Mortgage loans	144.9
Equity securities, at fair value	11.7
Other investments	327.8
Short-term investments, at fair value	450.1
Total investments	3,459.8
Cash	712.9
Accrued investment income	17.1
Premiums receivable	306.8
Reinsurance recoverables	2,981.6
Other intangible assets	186.1
Current income taxes receivable, net	53.2
Deferred tax asset, net	54.0
Ceded unearned premiums	387.6
Operating lease right-of-use assets	51.6
Other assets	190.8
Value of business acquired	176.3
Total assets	8,577.8
Liabilities
Reserves for losses and loss adjustment expenses	5,526.4
Unearned premiums	986.2
Accrued underwriting expenses and other liabilities	92.0
Ceded reinsurance payable, net	257.4
Funds held	49.9
Senior unsecured fixed rate notes	127.9
Junior subordinated debentures	241.0
Operating lease liabilities	52.1
Total liabilities assumed	7,332.9
Fair value of net assets acquired	1,244.9
Preferred stock	137.1
Bargain purchase gain	48.9
Fair value adjustment to assets acquired	114.2
Fair value adjustment to liabilities assumed	80.9
Common Stock
Business Acquisition [Line Items]
Equity interests issued and issuable	1,056.6
Employee Stock
Business Acquisition [Line Items]
Equity interests issued and issuable	$ 2.3