Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 52,699	$ 38,856	$ 125,529	$ 110,551
Net unrealized (losses) gains on investment securities available for sale:
Change in net unrealized losses	(38)	(948)	(464)	(2,841)
Net unrealized losses reclassified into net income	32	953	467	2,783
Net unrealized (losses) gains on investment securities available for sale	(6)	5	3	(58)
Net change in pension-related amounts:
Amortization of loss	245	403	735	1,211
Net change in pension-related amounts	245	403	735	1,211
Other comprehensive income	239	408	738	1,153
Income tax effect on:
Change in net unrealized losses on investment securities	11	245	120	733
Net unrealized losses reclassified into net income on investment securities	(9)	(246)	(121)	(718)
Pension-related amounts	(63)	(104)	(189)	(313)
Income tax provision on other comprehensive income	(61)	(105)	(190)	(298)
Other comprehensive income, net of tax	178	303	548	855
Comprehensive income	$ 52,877	$ 39,159	$ 126,077	$ 111,406