v3.26.1
INVESTMENTS - (Narrative) (Details)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
USD ($)
Jun. 30, 2025
USD ($)
Jun. 30, 2026
USD ($)
day
Jun. 30, 2025
USD ($)
Dec. 31, 2025
USD ($)
Schedule of Investments [Line Items]          
Assets Held-in-trust $ 8,200,000   $ 8,200,000   $ 8,600,000
Assets held by insurance regulators 2,200,000   2,200,000   2,500,000
Reverse repurchase agreements 120,600   $ 120,600   $ 59,200
Number of business days required for redemption notice | day     4    
Net income $ 663,078 $ 835,351 $ 956,457 $ 1,005,342  
RenaissanceRe Medici UCITS Fund          
Schedule of Investments [Line Items]          
Noncontrolling ownership percentage 35.00%   35.00%   34.30%
Fair Value Measured at Net Asset Value Per Share          
Schedule of Investments [Line Items]          
Fair value $ 3,156,249   $ 3,156,249   $ 2,775,499
RenaissanceRe Medici UCITS Fund          
Schedule of Investments [Line Items]          
Net income 3,200 $ 2,400 5,500 3,500  
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 interests     20,500 348,700  
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 interests       $ 140,000  
Insurance-linked securities funds | Fair Value Measured at Net Asset Value Per Share          
Schedule of Investments [Line Items]          
Fair value 160,000   160,000   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 $ 457,600   $ 457,600   $ 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