XML 50 R40.htm IDEA: XBRL DOCUMENT v3.24.3
Investments - Summary of Realized Gain and Loss and Investments in Unrealized Loss Position (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2024
Sep. 30, 2023
Sep. 30, 2024
Sep. 30, 2023
Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]          
Realized gross gains $ 360 $ 113 $ 415 $ 1,005  
Realized gross losses (292) (348) (2,128) (3,141)  
Impairment loss 0 $ 0 (523) $ (176)  
Fair Value          
Less than 12 months 436,716   436,716   $ 550,525
12 months or more 2,763,701   2,763,701   3,200,767
Total 3,200,417   3,200,417   3,751,292
Gross Unrealized Losses          
Less than 12 months (2,325)   (2,325)   (5,759)
12 months or more (246,686)   (246,686)   (330,678)
Total (249,011)   (249,011)   (336,437)
U.S. Treasury securities          
Fair Value          
Less than 12 months 63,050   63,050   139,398
12 months or more 315,890   315,890   355,921
Total 378,940   378,940   495,319
Gross Unrealized Losses          
Less than 12 months (11)   (11)   (1,075)
12 months or more (11,020)   (11,020)   (18,053)
Total (11,031)   (11,031)   (19,128)
U.S. agency securities          
Fair Value          
Less than 12 months         5,572
12 months or more         1,623
Total         7,195
Gross Unrealized Losses          
Less than 12 months         (2)
12 months or more         (2)
Total         (4)
U.S. agency mortgage-backed securities          
Fair Value          
Less than 12 months 98,220   98,220   129,359
12 months or more 677,515   677,515   654,018
Total 775,735   775,735   783,377
Gross Unrealized Losses          
Less than 12 months (796)   (796)   (1,616)
12 months or more (83,899)   (83,899)   (100,383)
Total (84,695)   (84,695)   (101,999)
Municipal debt securities          
Fair Value          
Less than 12 months 33,660   33,660   59,301
12 months or more 298,168   298,168   297,039
Total 331,828   331,828   356,340
Gross Unrealized Losses          
Less than 12 months (224)   (224)   (987)
12 months or more (34,333)   (34,333)   (43,462)
Total (34,557)   (34,557)   (44,449)
Non-U.S. government securities:          
Fair Value          
Less than 12 months 4,383   4,383   0
12 months or more 68,588   68,588   67,447
Total 72,971   72,971   67,447
Gross Unrealized Losses          
Less than 12 months (29)   (29)   0
12 months or more (8,708)   (8,708)   (10,069)
Total (8,737)   (8,737)   (10,069)
Corporate debt securities:          
Fair Value          
Less than 12 months 188,259   188,259   119,764
12 months or more 768,267   768,267   905,606
Total 956,526   956,526   1,025,370
Gross Unrealized Losses          
Less than 12 months (856)   (856)   (733)
12 months or more (63,255)   (63,255)   (87,170)
Total (64,111)   (64,111)   (87,903)
Residential and commercial mortgage securities          
Fair Value          
Less than 12 months 3,649   3,649   31,936
12 months or more 448,587   448,587   459,789
Total 452,236   452,236   491,725
Gross Unrealized Losses          
Less than 12 months (173)   (173)   (999)
12 months or more (35,944)   (35,944)   (52,510)
Total (36,117)   (36,117)   (53,509)
Asset-backed securities          
Fair Value          
Less than 12 months 45,495   45,495   65,195
12 months or more 186,686   186,686   459,324
Total 232,181   232,181   524,519
Gross Unrealized Losses          
Less than 12 months (236)   (236)   (347)
12 months or more (9,527)   (9,527)   (19,029)
Total $ (9,763)   $ (9,763)   $ (19,376)