v3.26.1
Supplemental Information about Changes to Accumulated Other Comprehensive Income (Loss) - Schedule of Reclassifications (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Unrealized investment (gains) losses on available for sale assets:        
Realized (gains) losses $ (7,138) $ 18,574 $ (5,660) $ 18,489
Amortization of (discount) premium (293,820) (282,169) (583,644) (562,783)
Other operating expense 116,251 108,293 229,986 217,039
Total before tax (354,887) (313,299) (689,019) (629,380)
Tax 67,140 60,550 130,746 122,068
Total after-tax (287,747) (252,749) (558,273) (507,312)
Reclassification out of Accumulated Other Comprehensive Income        
Unrealized investment (gains) losses on available for sale assets:        
Total after-tax (3,561) 8,423 (3,553) 5,837
Reclassification out of Accumulated Other Comprehensive Income | Unrealized investment (gains) losses on available for sale assets:        
Unrealized investment (gains) losses on available for sale assets:        
Realized (gains) losses (2,464) 12,837 (1,747) 12,009
Amortization of (discount) premium (2,152) (2,234) (4,438) (4,747)
Total before tax (4,616) 10,603 (6,185) 7,262
Tax 969 (2,227) 1,299 (1,525)
Total after-tax (3,647) 8,376 (4,886) 5,737
Reclassification out of Accumulated Other Comprehensive Income | Pension adjustments:        
Unrealized investment (gains) losses on available for sale assets:        
Total before tax 107 59 1,687 127
Tax (21) (12) (354) (27)
Total after-tax 86 47 1,333 100
Reclassification out of Accumulated Other Comprehensive Income | Amortization of prior service cost        
Unrealized investment (gains) losses on available for sale assets:        
Other operating expense 253 292 505 584
Reclassification out of Accumulated Other Comprehensive Income | Amortization of actuarial (gain) loss        
Unrealized investment (gains) losses on available for sale assets:        
Other operating expense $ (146) $ (233) $ 1,182 $ (457)