v3.26.1
DERIVATIVE INSTRUMENTS - Gains (Losses) on Derivatives Recognized in Net Income (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Unrealized and Realized Gains (Losses) Recognized in Earnings for Derivatives Not Designated As Hedges [Line Items]        
Unrealized and realized gains (losses) recognized in earnings for derivatives not designated as hedges $ (3,183) $ (23,050) $ 1,822 $ (15,137)
Relating to investment portfolio: | Foreign exchange forward contracts | Income Statement Location [Axis]: axs:NetInvestmentGainLoss        
Unrealized and Realized Gains (Losses) Recognized in Earnings for Derivatives Not Designated As Hedges [Line Items]        
Unrealized and realized gains (losses) recognized in earnings for derivatives not designated as hedges 34 (1,035) 180 (1,451)
Relating to underwriting portfolio: | Foreign exchange forward contracts | Income Statement Location [Axis]: us-gaap:ForeignCurrencyTransactionGainLossBeforeTax        
Unrealized and Realized Gains (Losses) Recognized in Earnings for Derivatives Not Designated As Hedges [Line Items]        
Unrealized and realized gains (losses) recognized in earnings for derivatives not designated as hedges $ (3,217) $ (22,015) $ 1,642 $ (13,686)