v3.26.1
Comprehensive Income/(Loss) - Schedule of Amounts Reclassified from Accumulated Other Comprehensive Income/(Loss) (Detail) - 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]        
Net securities gains reclassified into earnings $ (1,644) $ (1,410) $ (1,631) $ (1,092)
Provision for income taxes 24,846 13,558 47,635 12,886
Amortization of state tax rate change reclassified into earnings (243) (210) (486) (267)
Employee benefits (Non-interest expense) 19,148 18,857 36,759 31,827
Net effect on accumulated other comprehensive income/(loss) for the period (552) (364) (1,049) (579)
Accumulated Unrealized Gains (Losses) on Debt Securities Available for Sale [Member]        
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Net effect on accumulated other comprehensive income/(loss) for the period (321) (216) (591) (304)
Accumulated Defined Benefit Plans Adjustment [Member]        
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Net effect on accumulated other comprehensive income/(loss) for the period (231) (148) (458) (275)
Amounts Reclassified From Accumulated Other Comprehensive Income/(Loss) [Member] | Accumulated Unrealized Gains (Losses) on Debt Securities Available for Sale [Member]        
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Net securities gains reclassified into earnings (101) (9) (137) (50)
Provision for income taxes 23 3 32 14
Amortization of state tax rate change reclassified into earnings (243) (210) (486) (268)
Amounts Reclassified From Accumulated Other Comprehensive Income/(Loss) [Member] | Accumulated Defined Benefit Plans Adjustment [Member]        
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Provision for income taxes 69 46 136 91
Employee benefits (Non-interest expense) $ (300) $ (194) $ (594) $ (366)