Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 34,741	$ 32,542
Net unrealized gains (losses) on investment securities available for sale:
Change in net unrealized losses	(189)	(1,222)
Net unrealized losses reclassified into net income	224	1,165
Net unrealized gains (losses) on investment securities available for sale	35	(57)
Net change in pension-related amounts:
Amortization of loss	246	404
Net change in pension-related amounts	246	404
Other comprehensive income	281	347
Income tax effect on:
Change in net unrealized losses on investment securities	49	316
Net unrealized losses reclassified into net income on investment securities	(58)	(301)
Pension-related amounts	(63)	(105)
Income tax provision on other comprehensive income	(72)	(90)
Other comprehensive income, net of tax	209	257
Comprehensive income	$ 34,950	$ 32,799