CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 28,525	$ 24,119	$ 77,840	$ 71,450
Change in available-for-sale and transferred securities:
Unrealized holding gain (loss) on securities available-for-sale arising during the period	(80,532)	(14,411)	(302,137)	(20,656)
Reclassification adjust for amortization of unrealized losses on securities transferred to held-to-maturity	504	0	995	0
Reclassification adjustment for gains included in net income	0	0	0	(797)
Net securities gain (loss) activity during the period	(80,028)	(14,411)	(301,142)	(21,453)
Tax effect	16,806	3,026	63,239	4,505
Net of tax amount	(63,222)	(11,385)	(237,903)	(16,948)
Defined benefit pension plans:
Amortization of net actuarial loss	36	61	108	181
Net gain activity during the period	36	61	108	181
Tax effect	(9)	(15)	(27)	(45)
Net of tax amount	27	46	81	136
Total other comprehensive income (loss), net of tax	(63,195)	(11,339)	(237,822)	(16,812)
Comprehensive income (loss)	$ (34,670)	$ 12,780	$ (159,982)	$ 54,638