Stockholders' Equity (Details) $ / shares in Units, shares in Millions, $ in Millions			3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 16, 2024 USD ($)	Aug. 16, 2024 $ / shares	Sep. 30, 2024 USD ($) $ / shares	Sep. 30, 2023 USD ($)	Jun. 30, 2024 USD ($) shares	Sep. 30, 2024 USD ($) $ / shares	Sep. 30, 2023 USD ($)	May 07, 2024	Dec. 31, 2023 $ / shares
Class of Stock [Line Items]
Preferred stock, dividends declared (in dollars per share)			$ 437.50
Preferred stock, dividend rate (in percentage)		7.00%
Preferred shares par value (in dollars per share)		$ 1.00	1.00			$ 1.00			$ 1.00
Liquidation preference (in dollars per share)		$ 25,000	25,000			$ 25,000			$ 25,000
Fractional interest per one preference share								0.001
Depositary shares, dividends per share (in dollars per share)			$ 0.43750
Dividends declared | $	$ 2.6		$ 2.6	$ 2.6		$ 7.9	$ 7.9
Argo Group International Holdings, Inc. | Brookfield Reinsurance
Class of Stock [Line Items]
Number of shares purchased (in shares) | shares					200.0
Consideration transferred, equity interests issued | $					$ 200.0