Consolidated Statements of Comprehensive Income (Unaudited) - 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	$ 41,833	$ 46,567	$ 116,554	$ 119,792
Securities available for sale:
Unrealized holding losses on securities	(12,883)	(63,579)	(13,282)	(220,999)
Reclassification adjustment for losses realized in net income	0	0	16,816	0
Amortization of unrealized holding losses on securities transferred to the held to maturity category	2,947	1,207	7,527	969
Total securities available for sale	(9,936)	(62,372)	11,061	(220,030)
Derivative instruments:
Unrealized holding gains (losses) on derivative instruments	1,987	1,687	(1,606)	14,328
Total derivative instruments	1,987	1,687	(1,606)	14,328
Defined benefit pension and post-retirement benefit plans:
Amortization of net actuarial loss recognized in net periodic pension cost	86	31	258	93
Total defined benefit pension and post-retirement benefit plans	86	31	258	93
Other comprehensive (loss) income, net of tax	(7,863)	(60,654)	9,713	(205,609)
Comprehensive income (loss)	$ 33,970	$ (14,087)	$ 126,267	$ (85,817)