v3.26.1
Investments (Schedule of Available-For-Sale Securities by Contractual Maturity) (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Fixed maturities, available-for-sale    
Amortized Cost $ 3,775,708 $ 3,793,777
Total Fair Value 3,643,213 3,685,787
U.S. Treasury obligations    
Fixed maturities, available-for-sale    
Amortized Cost 187,671 224,114
Due in one year or less 34,896  
Due after one year through five years 123,730  
Due after five years through ten years 21,187  
Due after ten years 2,589  
Total Fair Value 182,402 219,402
U.S. Government-sponsored enterprise obligations    
Fixed maturities, available-for-sale    
Amortized Cost 9,131 10,124
Due in one year or less 1,963  
Due after one year through five years 4,147  
Due after five years through ten years 753  
Due after ten years 1,983  
Total Fair Value 8,846 9,852
State and municipal bonds    
Fixed maturities, available-for-sale    
Amortized Cost 447,641 439,082
Due in one year or less 23,273  
Due after one year through five years 159,273  
Due after five years through ten years 130,129  
Due after ten years 125,057  
Total Fair Value 437,732 430,063
Corporate debt    
Fixed maturities, available-for-sale    
Amortized Cost 1,805,088 1,807,392
Due in one year or less 212,980  
Due after one year through five years 834,028  
Due after five years through ten years 527,565  
Due after ten years 168,749  
Total Fair Value 1,743,322 1,761,514
Residential mortgage-backed securities    
Fixed maturities, available-for-sale    
Amortized Cost 634,414 629,348
Total Fair Value 592,619 591,841
Agency commercial mortgage-backed securities    
Fixed maturities, available-for-sale    
Amortized Cost 5,920 6,062
Total Fair Value 5,205 5,360
Other commercial mortgage-backed securities    
Fixed maturities, available-for-sale    
Amortized Cost 224,308 214,535
Total Fair Value 217,245 208,121
Other asset-backed securities    
Fixed maturities, available-for-sale    
Amortized Cost 461,535 463,120
Total Fair Value $ 455,842 $ 459,634