Accumulated Other Comprehensive Income (Loss), Reclassifications out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022
Reclassification Adjustment Out of Accumulated Other Comprehensive Loss [Abstract]
Salaries and employee benefits	$ 13,122		$ 11,464		$ 26,405	$ 20,703
Income tax benefit	5,451		5,591		11,360	11,216
Net income	16,372	$ 17,746	17,871	$ 17,089	34,118	34,960
Reclassification Out of Accumulated Other Comprehensive Loss [Member]
Reclassification Adjustment Out of Accumulated Other Comprehensive Loss [Abstract]
Net income	82		224		164	489
Amortization of Pension and Postretirement Benefit Items [Member] | Reclassification Out of Accumulated Other Comprehensive Loss [Member]
Reclassification Adjustment Out of Accumulated Other Comprehensive Loss [Abstract]
Income tax benefit	(29)		(79)		(58)	(172)
Net income	82		224		164	489
Amortization of Net Actuarial Gain [Member] | Reclassification Out of Accumulated Other Comprehensive Loss [Member]
Reclassification Adjustment Out of Accumulated Other Comprehensive Loss [Abstract]
Salaries and employee benefits	114		426		228	504
Amortization of Prior Service (Cost) Credit [Member] | Reclassification Out of Accumulated Other Comprehensive Loss [Member]
Reclassification Adjustment Out of Accumulated Other Comprehensive Loss [Abstract]
Salaries and employee benefits	$ (3)		$ (123)		$ (6)	$ 157