Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 38,089	$ 39,153	$ 72,830	$ 71,695
Net unrealized (losses) gains on investment securities available for sale:
Change in net unrealized losses	(237)	(671)	(426)	(1,893)
Net unrealized losses reclassified into net income	211	665	435	1,830
Net unrealized (losses) gains on investment securities available for sale	(26)	(6)	9	(63)
Net change in pension-related amounts:
Amortization of loss	244	404	490	808
Net change in pension-related amounts	244	404	490	808
Other comprehensive income	218	398	499	745
Income tax effect on:
Change in net unrealized losses on investment securities	60	172	109	488
Net unrealized losses reclassified into net income on investment securities	(54)	(171)	(112)	(472)
Pension-related amounts	(63)	(104)	(126)	(209)
Income tax provision on other comprehensive income	(57)	(103)	(129)	(193)
Other comprehensive income, net of tax	161	295	370	552
Comprehensive income	$ 38,250	$ 39,448	$ 73,200	$ 72,247