v3.26.3
INVESTMENTS - (Narrative) (Details)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2026
USD ($)
Sep. 30, 2025
USD ($)
Sep. 30, 2026
USD ($)
day
Sep. 30, 2025
USD ($)
Dec. 31, 2025
USD ($)
Schedule of Investments [Line Items]          
Assets Held-in-trust $ 7,800,000   $ 7,800,000   $ 8,600,000
Assets held by insurance regulators 2,100,000   2,100,000   2,500,000
Reverse repurchase agreements 44,600   $ 44,600   $ 59,200
Number of business days required for redemption notice | day     4    
Net income $ (152,541) $ 916,510 $ 803,916 $ 1,921,852  
RenaissanceRe Medici UCITS Fund          
Schedule of Investments [Line Items]          
Noncontrolling ownership percentage 35.10%   35.10%   34.30%
Fair Value Measured at Net Asset Value Per Share          
Schedule of Investments [Line Items]          
Fair value $ 3,267,118   $ 3,267,118   $ 2,775,499
RenaissanceRe Medici UCITS Fund          
Schedule of Investments [Line Items]          
Net income 7,000 $ 7,500 12,500 11,000  
RenaissanceRe Medici UCITS Fund          
Schedule of Investments [Line Items]          
Transfer in kind from existing investors       316,500  
RenaissanceRe Medici UCITS Fund | Third-Party Investors          
Schedule of Investments [Line Items]          
Sale of shares to redeemable noncontrolling interest     20,500 356,500  
Redemption of shares from redeemable noncontrolling interest     23,400    
RenaissanceRe Medici UCITS Fund | RenaissanceRe Holdings Ltd.          
Schedule of Investments [Line Items]          
Sale of shares to redeemable noncontrolling interest       $ 140,000  
Insurance-linked securities funds | Fair Value Measured at Net Asset Value Per Share          
Schedule of Investments [Line Items]          
Fair value 167,000   167,000   154,500
Insurance-linked securities funds | RenaissanceRe Medici UCITS Fund | Fair Value Measured at Net Asset Value Per Share          
Schedule of Investments [Line Items]          
Fair value $ 475,800   $ 475,800   $ 449,900
Minimum | Private credit funds          
Schedule of Investments [Line Items]          
Liquidation period for fund assets     5 years    
Minimum | Direct private equity investments          
Schedule of Investments [Line Items]          
Liquidation period for fund assets     5 years    
Minimum | Catastrophe bonds          
Schedule of Investments [Line Items]          
Maturity period     1 year    
Maximum | Private credit funds          
Schedule of Investments [Line Items]          
Liquidation period for fund assets     10 years    
Maximum | Direct private equity investments          
Schedule of Investments [Line Items]          
Liquidation period for fund assets     10 years    
Maximum | Catastrophe bonds          
Schedule of Investments [Line Items]          
Maturity period     5 years