Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Statement of Comprehensive Income [Abstract]
Net income	$ 35,693	$ 42,341
Debt securities available-for-sale:
Net change in unrealized (losses) gains on debt securities available-for-sale	(10,903)	36,610
Related income tax effect	2,785	(8,782)
Net securities losses reclassified into earnings		151
Related income tax effect	(59)	(37)
Net effect on other comprehensive (loss) income for the period	(8,177)	27,942
Defined benefit plans:
Amortization of net (gain) loss and prior service costs	(101)	98
Related income tax effect	49	(23)
Net effect on other comprehensive (loss) income for the period	(52)	75
Total other comprehensive (loss) income	(8,229)	28,017
Comprehensive income	$ 27,464	$ 70,358