Allowance for Credit Losses (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022 USD ($) item	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($) item	Jun. 30, 2021 USD ($)
Allowance for credit losses
Number of classes existing in loan and lease portfolio | item	9		9
Changes in allowance for loan and lease losses
Balance at the beginning of the period	$ 129,959	$ 139,550	$ 127,492	$ 140,654
Charge-offs	234	794	451	5,246
Recoveries	637	630	1,088	1,580
Net charge-offs (recoveries)	(403)	164	(637)	3,666
Provision (recovery of provision)	2,503	(3,025)	4,736	(627)
Balance at the end of the period	132,865	136,361	132,865	136,361
Commercial and agricultural
Changes in allowance for loan and lease losses
Balance at the beginning of the period	15,598	15,451	15,409	16,680
Charge-offs	39	285	39	286
Recoveries	3	141	7	518
Net charge-offs (recoveries)	36	144	32	(232)
Provision (recovery of provision)	548	(475)	733	(2,080)
Balance at the end of the period	16,110	14,832	16,110	14,832
Solar
Changes in allowance for loan and lease losses
Balance at the beginning of the period	6,417	5,758	6,585	5,549
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Net charge-offs (recoveries)	0	0	0	0
Provision (recovery of provision)	235	109	67	318
Balance at the end of the period	6,652	5,867	6,652	5,867
Auto and light truck
Changes in allowance for loan and lease losses
Balance at the beginning of the period	19,521	29,343	19,624	28,926
Charge-offs	32	367	32	4,653
Recoveries	56	136	121	185
Net charge-offs (recoveries)	(24)	231	(89)	4,468
Provision (recovery of provision)	(488)	(1,891)	(656)	2,763
Balance at the end of the period	19,057	27,221	19,057	27,221
Medium and heavy duty truck
Changes in allowance for loan and lease losses
Balance at the beginning of the period	6,049	6,271	6,015	6,400
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Net charge-offs (recoveries)	0	0	0	0
Provision (recovery of provision)	660	(383)	694	(512)
Balance at the end of the period	6,709	5,888	6,709	5,888
Aircraft
Changes in allowance for loan and lease losses
Balance at the beginning of the period	35,968	35,219	33,628	34,053
Charge-offs	0	0	0	0
Recoveries	161	241	477	360
Net charge-offs (recoveries)	(161)	(241)	(477)	(360)
Provision (recovery of provision)	858	(159)	2,882	888
Balance at the end of the period	36,987	35,301	36,987	35,301
Construction equipment
Changes in allowance for loan and lease losses
Balance at the beginning of the period	20,041	16,309	19,673	19,166
Charge-offs	0	0	48	8
Recoveries	0	0	0	254
Net charge-offs (recoveries)	0	0	48	(246)
Provision (recovery of provision)	1,130	1,599	1,546	(1,504)
Balance at the end of the period	21,171	17,908	21,171	17,908
Commercial real estate
Changes in allowance for loan and lease losses
Balance at the beginning of the period	19,246	24,334	19,691	22,758
Charge-offs	0	0	0	0
Recoveries	26	4	26	19
Net charge-offs (recoveries)	(26)	(4)	(26)	(19)
Provision (recovery of provision)	(856)	(1,760)	(1,301)	(199)
Balance at the end of the period	18,416	22,578	18,416	22,578
Residential real estate and home equity
Changes in allowance for loan and lease losses
Balance at the beginning of the period	5,218	5,163	5,084	5,374
Charge-offs	6	37	10	42
Recoveries	127	10	128	11
Net charge-offs (recoveries)	(121)	27	(118)	31
Provision (recovery of provision)	440	(70)	577	(277)
Balance at the end of the period	5,779	5,066	5,779	5,066
Consumer
Changes in allowance for loan and lease losses
Balance at the beginning of the period	1,901	1,702	1,783	1,748
Charge-offs	157	105	322	257
Recoveries	264	98	329	233
Net charge-offs (recoveries)	(107)	7	(7)	24
Provision (recovery of provision)	(24)	5	194	(24)
Balance at the end of the period	$ 1,984	$ 1,700	$ 1,984	$ 1,700