Allowance for Credit Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Changes in allowance for loan and lease losses
Balance at the beginning of the period	$ 139,268	$ 127,492	$ 140,654
Charge-offs	6,648	3,409	12,523
Recoveries	9,066	1,940	3,664
Net charge-offs (recoveries)	(2,418)	1,469	8,859
Provision (recovery of provision)	5,866	13,245	(4,303)
Balance at the end of the period	147,552	139,268	127,492
Commercial and agricultural
Changes in allowance for loan and lease losses
Balance at the beginning of the period	14,635	15,409	16,680
Charge-offs	4,305	625	2,930
Recoveries	243	56	812
Net charge-offs (recoveries)	4,062	569	2,118
Provision (recovery of provision)	6,812	(205)	847
Balance at the end of the period	17,385	14,635	15,409
Renewable energy
Changes in allowance for loan and lease losses
Balance at the beginning of the period	7,217	6,585	5,549
Charge-offs	0	0	0
Recoveries	0	0	0
Net charge-offs (recoveries)	0	0	0
Provision (recovery of provision)	(607)	632	1,036
Balance at the end of the period	6,610	7,217	6,585
Auto and light truck
Changes in allowance for loan and lease losses
Balance at the beginning of the period	18,634	19,624	28,926
Charge-offs	729	118	7,797
Recoveries	5,591	417	1,316
Net charge-offs (recoveries)	(4,862)	(299)	6,481
Provision (recovery of provision)	(6,638)	(1,289)	(2,821)
Balance at the end of the period	16,858	18,634	19,624
Medium and heavy duty truck
Changes in allowance for loan and lease losses
Balance at the beginning of the period	7,566	6,015	6,400
Charge-offs	0	0	0
Recoveries	12	0	0
Net charge-offs (recoveries)	(12)	0	0
Provision (recovery of provision)	1,387	1,551	(385)
Balance at the end of the period	8,965	7,566	6,015
Aircraft
Changes in allowance for loan and lease losses
Balance at the beginning of the period	41,093	33,628	34,053
Charge-offs	0	0	0
Recoveries	967	785	687
Net charge-offs (recoveries)	(967)	(785)	(687)
Provision (recovery of provision)	(4,407)	6,680	(1,112)
Balance at the end of the period	37,653	41,093	33,628
Construction equipment
Changes in allowance for loan and lease losses
Balance at the beginning of the period	24,039	19,673	19,166
Charge-offs	54	1,114	856
Recoveries	1,656	17	473
Net charge-offs (recoveries)	(1,602)	1,097	383
Provision (recovery of provision)	869	5,463	890
Balance at the end of the period	26,510	24,039	19,673
Commercial real estate
Changes in allowance for loan and lease losses
Balance at the beginning of the period	17,431	19,691	22,758
Charge-offs	248	538	0
Recoveries	11	45	19
Net charge-offs (recoveries)	237	493	(19)
Provision (recovery of provision)	6,496	(1,767)	(3,086)
Balance at the end of the period	23,690	17,431	19,691
Residential real estate and home equity
Changes in allowance for loan and lease losses
Balance at the beginning of the period	6,478	5,084	5,374
Charge-offs	101	284	228
Recoveries	334	160	16
Net charge-offs (recoveries)	(233)	124	212
Provision (recovery of provision)	987	1,518	(78)
Balance at the end of the period	7,698	6,478	5,084
Consumer
Changes in allowance for loan and lease losses
Balance at the beginning of the period	2,175	1,783	1,748
Charge-offs	1,211	730	712
Recoveries	252	460	341
Net charge-offs (recoveries)	959	270	371
Provision (recovery of provision)	967	662	406
Balance at the end of the period	$ 2,183	$ 2,175	$ 1,783