Accumulated Other Comprehensive Loss - Reclassification from Each Component of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Reclassification Out Of Accumulated Other Comprehensive Loss
Included in interest income.	$ 420,105	$ 393,548
Tax effect	(33,062)	(33,173)
Total net of tax	106,058	96,280
Amortization of actuarial net loss	32,340	29,019
Amounts Reclassified from Accumulated Other Comprehensive Loss
Reclassification Out Of Accumulated Other Comprehensive Loss
Total net of tax	130	187
Amounts Reclassified from Accumulated Other Comprehensive Loss | Unrealized gains on derivatives (cash flow hedges) before tax
Reclassification Out Of Accumulated Other Comprehensive Loss
Included in interest income.	301	298
Tax effect	(83)	(76)
Total net of tax	218	222
Amounts Reclassified from Accumulated Other Comprehensive Loss | Defined benefit pension plan
Reclassification Out Of Accumulated Other Comprehensive Loss
Tax effect	33	14
Total net of tax	(88)	(35)
Amortization of actuarial net loss	$ (121)	$ (49)