v3.26.1
Reinsurance (Effect Of Reinsurance And Retrocessional Reinsurance On Premiums Written And Earned) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Effects of Reinsurance [Line Items]        
Direct premiums written $ 3,418,250 $ 3,236,526 $ 6,415,440 $ 6,146,183
Direct premiums earned 3,062,504 3,042,781 6,142,702 5,977,509
Assumed premiums written 1,153,924 1,907,965 1,941,756 3,216,538
Assumed premiums earned 820,668 768,201 1,529,246 1,450,552
Ceded premiums written (2,448,518) (2,901,140) (4,388,494) (4,809,079)
Ceded premiums earned (1,811,394) (1,669,291) (3,551,284) (3,196,996)
Net premiums written 2,123,656 2,243,351 3,968,702 4,553,642
Net premiums earned 2,071,778 2,141,691 4,120,664 4,231,065
Underwriting        
Effects of Reinsurance [Line Items]        
Direct premiums written 2,282,932 2,414,799 4,352,386 4,550,772
Direct premiums earned 2,209,012 2,210,284 4,431,670 4,405,767
Assumed premiums written 184,138 471,869 403,912 1,200,912
Assumed premiums earned 316,465 451,071 657,134 889,116
Ceded premiums written (343,419) (643,567) (787,764) (1,198,292)
Ceded premiums earned (453,697) (519,923) (968,255) (1,064,079)
Net premiums written 2,123,651 2,243,101 3,968,534 4,553,392
Net premiums earned 2,071,780 2,141,432 4,120,549 4,230,804
Fronting        
Effects of Reinsurance [Line Items]        
Direct premiums written 1,135,318 821,727 2,063,054 1,595,411
Direct premiums earned 853,492 832,497 1,711,032 1,571,742
Assumed premiums written 969,786 1,436,096 1,537,844 2,015,626
Assumed premiums earned 504,203 317,130 872,112 561,436
Ceded premiums written (2,105,099) (2,257,573) (3,600,730) (3,610,787)
Ceded premiums earned (1,357,697) (1,149,368) (2,583,029) (2,132,917)
Net premiums written 5 250 168 250
Net premiums earned $ (2) $ 259 $ 115 $ 261