v3.26.3
CHANGE IN ACCUMULATED OTHER COMPREHENSIVE LOSS - Schedule of Components of Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Income taxes $ (28,309) $ (24,405) $ (82,743) $ (68,825)
Transition obligation (93,817) (91,661) (281,471) (263,283)
Income before taxes 117,620 100,872 343,228 283,380
Reclassification out of Accumulated Other Comprehensive Income (Loss)        
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Total reclassifications (6,638) 3,086 (9,376) 13,717
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Net unrealized holding losses on securities transferred between available-for-sale and held-to-maturity:        
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Amortization of net unrealized losses to income during the period 3,985 4,433 11,578 12,927
Income taxes (957) (1,063) (2,779) (3,102)
Total reclassifications 3,028 3,370 8,799 9,825
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Amortization of defined benefit post-retirement plan-related items:        
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Income taxes 28 22 83 66
Actuarial gains (101) (72) (304) (217)
Income before taxes (115) (91) (346) (274)
Total reclassifications (87) (69) (263) (208)
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Prior service credits        
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Prior service credits (14) (19) (42) (57)
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Net change in fair value of derivatives used for cash flow hedges        
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Amortization of net unrealized losses to income during the period (12,604) (283) (23,568) 5,395
Income taxes 3,025 68 5,656 (1,295)
Total reclassifications $ (9,579) $ (215) $ (17,912) $ 4,100