v3.26.3
Investments - Schedule of Available For Sale Maturity (Details) - USD ($)
$ in Thousands
Sep. 30, 2026
Dec. 31, 2025
Amortized Cost    
Amortized Cost $ 6,293,773 $ 6,279,693
Fair Value    
Fair Value 5,871,983 6,104,085
U.S. Treasury securities:    
Amortized Cost    
Due in 1 year 49,900  
Due after 1 but within 5 years 241,366  
Due after 5 but within 10 years 23,411  
Due after 10 years 14,551  
Subtotal 329,228  
Amortized Cost 329,228 373,567
Fair Value    
Due in 1 year 49,746  
Due after 1 but within 5 years 234,478  
Due after 5 but within 10 years 22,084  
Due after 10 years 11,536  
Subtotal 317,844  
Fair Value 317,844 369,712
Municipal debt securities    
Amortized Cost    
Due in 1 year 15,829  
Due after 1 but within 5 years 95,418  
Due after 5 but within 10 years 146,974  
Due after 10 years 372,155  
Subtotal 630,376  
Amortized Cost 630,376 641,153
Fair Value    
Due in 1 year 15,727  
Due after 1 but within 5 years 90,373  
Due after 5 but within 10 years 133,313  
Due after 10 years 323,937  
Subtotal 563,350  
Fair Value 563,350 610,411
Non-U.S. government securities    
Amortized Cost    
Due in 1 year 10,132  
Due after 1 but within 5 years 4,301  
Due after 5 but within 10 years 9,595  
Due after 10 years 29,397  
Subtotal 53,425  
Amortized Cost 53,425 64,470
Fair Value    
Due in 1 year 10,038  
Due after 1 but within 5 years 3,998  
Due after 5 but within 10 years 7,988  
Due after 10 years 20,145  
Subtotal 42,169  
Fair Value 42,169 56,024
Corporate debt securities:    
Amortized Cost    
Due in 1 year 147,131  
Due after 1 but within 5 years 633,953  
Due after 5 but within 10 years 1,102,119  
Due after 10 years 193,312  
Subtotal 2,076,515  
Amortized Cost 2,076,515 2,017,246
Fair Value    
Due in 1 year 146,248  
Due after 1 but within 5 years 599,524  
Due after 5 but within 10 years 1,033,941  
Due after 10 years 153,817  
Subtotal 1,933,530  
Fair Value 1,933,530 1,980,080
U.S. agency mortgage-backed securities    
Amortized Cost    
Amortized Cost 1,263,239 1,243,823
Fair Value    
Fair Value 1,125,165 1,174,895
Residential and commercial mortgage securities    
Amortized Cost    
Amortized Cost 487,182 486,441
Fair Value    
Fair Value 457,485 464,105
Asset-backed securities    
Amortized Cost    
Amortized Cost 949,658 804,501
Fair Value    
Fair Value 928,298 800,366
Money market funds    
Amortized Cost    
Amortized Cost 504,150 648,492
Fair Value    
Fair Value $ 504,142 $ 648,492