Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Statement of Comprehensive Income [Abstract]
Net income	$ 28,916	$ 44,880	$ 64,609	$ 87,221
Debt securities available-for-sale:
Net change in unrealized losses on debt securities available-for-sale	(210)	(40,018)	(11,113)	(3,408)
Related income tax effect	50	9,709	2,835	927
Net securities losses reclassified into earnings	12	8	12	159
Related income tax effect	(61)	(2)	(119)	(39)
Net effect on other comprehensive loss for the period	(209)	(30,303)	(8,385)	(2,361)
Defined benefit plans:
Amortization of net (gain) loss and prior service costs	(101)	99	(202)	198
Related income tax effect	24	(24)	72	(48)
Net effect on other comprehensive (loss) income for the period	(77)	75	(130)	150
Total other comprehensive loss	(286)	(30,228)	(8,515)	(2,211)
Comprehensive income	$ 28,630	$ 14,652	$ 56,094	$ 85,010