v3.26.3
Investments - Schedule of Available for Sale (Details) - USD ($)
$ in Thousands
Sep. 30, 2026
Dec. 31, 2025
Investments available for sale    
Amortized Cost $ 6,293,773 $ 6,279,693
Unrealized Gains 1,057 37,685
Unrealized Losses (422,847) (213,293)
Fair Value 5,871,983 6,104,085
U.S. Treasury securities    
Investments available for sale    
Amortized Cost 329,228 373,567
Unrealized Gains 0 2,121
Unrealized Losses (11,384) (5,976)
Fair Value 317,844 369,712
U.S. agency mortgage-backed securities    
Investments available for sale    
Amortized Cost 1,263,239 1,243,823
Unrealized Gains 38 7,822
Unrealized Losses (138,112) (76,750)
Fair Value 1,125,165 1,174,895
Municipal debt securities    
Investments available for sale    
Amortized Cost 630,376 641,153
Unrealized Gains 37 5,483
Unrealized Losses (67,063) (36,225)
Fair Value 563,350 610,411
Non-U.S. government securities    
Investments available for sale    
Amortized Cost 53,425 64,470
Unrealized Gains 0 0
Unrealized Losses (11,256) (8,446)
Fair Value 42,169 56,024
Corporate debt securities    
Investments available for sale    
Amortized Cost 2,076,515 2,017,246
Unrealized Gains 32 17,381
Unrealized Losses (143,017) (54,547)
Fair Value 1,933,530 1,980,080
Residential and commercial mortgage securities    
Investments available for sale    
Amortized Cost 487,182 486,441
Unrealized Gains 339 1,046
Unrealized Losses (30,036) (23,382)
Fair Value 457,485 464,105
Asset-backed securities    
Investments available for sale    
Amortized Cost 949,658 804,501
Unrealized Gains 611 3,832
Unrealized Losses (21,971) (7,967)
Fair Value 928,298 800,366
Money market funds    
Investments available for sale    
Amortized Cost 504,150 648,492
Unrealized Gains 0 0
Unrealized Losses (8) 0
Fair Value $ 504,142 $ 648,492