Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 144,678	$ 166,068	$ 175,892
Securities available for sale:
Unrealized holding gains (losses) on securities	15,128	(214,351)	(38,371)
Reclassification adjustment for losses (gains) realized in net income	31,063	0	(1,618)
Amortization of unrealized holding losses (gains) on securities transferred to the held to maturity category	10,091	3,701	(54)
Total securities available for sale	56,282	(210,650)	(40,043)
Derivative instruments:
Unrealized holding (losses) gains on derivative instruments	(1,905)	14,993	8,087
Reclassification adjustment for gains realized in net income related to swap termination	0	0	(3,486)
Total derivative instruments	(1,905)	14,993	4,601
Defined benefit pension and post-retirement benefit plans:
Net gain (loss) arising during the period	60	(3,062)	(264)
Amortization of net actuarial loss recognized in net periodic pension cost	344	125	195
Total defined benefit pension and post-retirement benefit plans	404	(2,937)	(69)
Other comprehensive income (loss), net of tax	54,781	(198,594)	(35,511)
Comprehensive income (loss)	$ 199,459	$ (32,526)	$ 140,381