ACCUMULATED OTHER COMPREHENSIVE INCOME/ (LOSS) - Reclassification Adjustments Out of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Investment securities gains/ (losses)	$ 0	$ (345)	$ 212
Interest and dividends on investment securities	637,524	495,667	450,284
Recognized net actuarial loss	526	783	909
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	(8,157)	0	(560)
Income before taxes	164,135	222,358	311,659
Tax expense (benefit)	(41,291)	(56,059)	(76,552)
Net income	122,844	166,299	235,107
Reclassification out of Accumulated Other Comprehensive Income | Unrealized Gains/ (Losses) on Investments Available-for-Sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Investment securities gains/ (losses)	0	(345)	212
Income before taxes	0	(345)	212
Tax expense (benefit)	0	88	(54)
Net income	0	(257)	158
Reclassification out of Accumulated Other Comprehensive Income | Unrealized Losses on Debt Securities Transferred from Available-for-Sale to Held-to-Maturity
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and dividends on investment securities	(1,726)	(2,245)	0
Income before taxes	(1,726)	(2,245)	0
Tax expense (benefit)	452	598	0
Net income	(1,274)	(1,647)	0
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Line Items]
Recognized net actuarial loss	(526)	(783)	(909)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	(8,157)	0	(560)
Reclassification out of Accumulated Other Comprehensive Income | Defined Benefit Pension Plan
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income before taxes	(8,683)	(783)	(1,469)
Tax expense (benefit)	2,212	199	376
Net income	$ (6,471)	$ (584)	$ (1,093)