v3.26.1
CHANGE IN ACCUMULATED OTHER COMPREHENSIVE LOSS - Schedule of Components of Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Income taxes $ (26,795) $ (23,319) $ (54,434) $ (44,420)
Transition obligation (95,767) (89,145) (187,654) (171,622)
Income before taxes 111,124 95,540 225,608 182,508
Reclassification out of Accumulated Other Comprehensive Income (Loss)        
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Total reclassifications (3,425) 4,637 (2,737) 10,631
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 3,821 4,299 7,593 8,494
Income taxes (917) (1,032) (1,822) (2,039)
Total reclassifications 2,904 3,267 5,771 6,455
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) (28) (38)
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Amortization of defined benefit pension plan-related items:        
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Income taxes 28 22 56 44
Actuarial gains (102) (73) (203) (145)
Income before taxes (116) (92) (231) (183)
Total reclassifications (88) (70) (175) (139)
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 (8,212) 1,895 (10,964) 5,678
Income taxes 1,971 (455) 2,631 (1,363)
Total reclassifications $ (6,241) $ 1,440 $ (8,333) $ 4,315