v3.26.1
Comprehensive Income (Loss) - Schedule of Components of Comprehensive Income-Gross and Net of Tax (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Gross        
Income (loss) before federal income tax $ 162,845 $ 108,905 $ 287,047 $ 247,791
Other comprehensive income (loss) (3,131) 52,438 (92,934) 134,433
Comprehensive income (loss) 159,714 161,343 194,113 382,224
Tax        
Net income 33,460 22,962 59,986 51,952
Other comprehensive income (loss) (654) 11,012 (19,516) 28,230
Comprehensive income (loss) 32,806 33,974 40,470 80,182
Net        
Net income (loss) 129,385 85,943 227,061 195,839
OCI before reclassifications     (86,060)  
Reclassifications     12,642  
Other comprehensive income (loss) (2,477) 41,426 (73,418) 106,203
Comprehensive income (loss) 126,908 127,369 153,643 302,042
Investments Subtotal        
Gross        
Other comprehensive income (loss) (3,937) 51,565 (94,547) 132,688
Tax        
Other comprehensive income (loss) (823) 10,828 (19,855) 27,863
Net        
OCI before reclassifications     (86,060)  
Reclassifications     11,368  
Other comprehensive income (loss) (3,114) 40,737 (74,692) 104,825
Net realized (gains) losses on disposals and intent-to-sell AFS securities        
Gross        
OCI before reclassifications (13,709) 41,864 (95,581) 111,124
Reclassifications 3,318 (434) 4,981 (708)
Tax        
OCI before reclassifications (2,874) 8,790 (20,072) 23,335
Reclassifications 696 (91) 1,046 (149)
Net        
OCI before reclassifications (10,835) 33,074 (75,509) 87,789
Reclassifications 2,622 (343) 3,935 (559)
Other comprehensive income (loss)     (71,574)  
Credit loss related        
Gross        
OCI before reclassifications 5,199 11,022 (13,356) 23,788
Reclassifications 1,255 (887) 9,409 (1,516)
Tax        
OCI before reclassifications 1,092 2,315 (2,805) 4,995
Reclassifications 263 (186) 1,976 (318)
Net        
OCI before reclassifications 4,107 8,707 (10,551) 18,793
Reclassifications 992 (701) 7,433 (1,198)
Other comprehensive income (loss)     (3,118)  
Defined benefit pension and post-retirement life plans        
Gross        
Other comprehensive income (loss) 806 873 1,613 1,745
Tax        
Other comprehensive income (loss) 169 184 339 367
Net        
OCI before reclassifications     0  
Reclassifications     1,274  
Other comprehensive income (loss) 637 689 1,274 1,378
Net actuarial (gain) loss        
Gross        
Reclassifications 806 873 1,613 1,745
Tax        
Reclassifications 169 184 339 367
Net        
Reclassifications $ 637 $ 689 $ 1,274 $ 1,378