v3.26.1
Investments (Schedule of Investments Held in an Unrealized Loss Position) (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Fair value    
Fair Value $ 2,390,905 $ 2,109,823
Less than 12 months, Fair Value 928,094 461,509
12 months or longer, Fair Value 1,462,811 1,648,314
Unrealized Loss    
Unrealized Loss 145,648 133,744
Less than 12 months, Unrealized Loss 27,519 20,025
12 months or longer, Unrealized Loss 118,129 113,719
U.S. Treasury obligations    
Fair value    
Fair Value 138,974 157,145
Less than 12 months, Fair Value 43,751 18,979
12 months or longer, Fair Value 95,223 138,166
Unrealized Loss    
Unrealized Loss 5,759 5,583
Less than 12 months, Unrealized Loss 1,253 706
12 months or longer, Unrealized Loss 4,506 4,877
U.S. Government-sponsored enterprise obligations    
Fair value    
Fair Value 7,819 8,819
Less than 12 months, Fair Value 4,900 0
12 months or longer, Fair Value 2,919 8,819
Unrealized Loss    
Unrealized Loss 287 281
Less than 12 months, Unrealized Loss 84 0
12 months or longer, Unrealized Loss 203 281
State and municipal bonds    
Fair value    
Fair Value 267,976 271,950
Less than 12 months, Fair Value 68,256 62,940
12 months or longer, Fair Value 199,720 209,010
Unrealized Loss    
Unrealized Loss 13,648 13,316
Less than 12 months, Unrealized Loss 2,656 2,863
12 months or longer, Unrealized Loss 10,992 10,453
Corporate debt    
Fair value    
Fair Value 1,230,806 1,066,878
Less than 12 months, Fair Value 468,453 191,825
12 months or longer, Fair Value 762,353 875,053
Unrealized Loss    
Unrealized Loss 64,998 57,043
Less than 12 months, Unrealized Loss 16,568 10,359
12 months or longer, Unrealized Loss 48,430 46,684
Residential mortgage-backed securities    
Fair value    
Fair Value 378,365 317,483
Less than 12 months, Fair Value 148,276 81,600
12 months or longer, Fair Value 230,089 235,883
Unrealized Loss    
Unrealized Loss 45,269 42,956
Less than 12 months, Unrealized Loss 5,105 4,130
12 months or longer, Unrealized Loss 40,164 38,826
Agency commercial mortgage-backed securities    
Fair value    
Fair Value 4,754 4,909
Less than 12 months, Fair Value 470 1,059
12 months or longer, Fair Value 4,284 3,850
Unrealized Loss    
Unrealized Loss 721 712
Less than 12 months, Unrealized Loss 8 128
12 months or longer, Unrealized Loss 713 584
Other commercial mortgage-backed securities    
Fair value    
Fair Value 151,942 133,487
Less than 12 months, Fair Value 60,456 40,131
12 months or longer, Fair Value 91,486 93,356
Unrealized Loss    
Unrealized Loss 7,487 7,203
Less than 12 months, Unrealized Loss 465 426
12 months or longer, Unrealized Loss 7,022 6,777
Other asset-backed securities    
Fair value    
Fair Value 210,269 149,152
Less than 12 months, Fair Value 133,532 64,975
12 months or longer, Fair Value 76,737 84,177
Unrealized Loss    
Unrealized Loss 7,479 6,650
Less than 12 months, Unrealized Loss 1,380 1,413
12 months or longer, Unrealized Loss $ 6,099 $ 5,237