Allowance for Credit Losses (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($) item	Mar. 31, 2020 USD ($)
Allowance for credit losses
Number of classes existing in loan and lease portfolio | item	9
Changes in allowance for loan and lease losses
Balance at the beginning of the period	$ 140,654	$ 111,254	[1]
Charge-offs	4,452	2,838
Recoveries	950	1,029
Net charge-offs (recoveries)	3,502	1,809
Provision (recovery of provision)	2,398	11,353	[1]
Balance at the end of the period	139,550	120,798	[1]
Commercial and agricultural
Changes in allowance for loan and lease losses
Balance at the beginning of the period	16,680	20,926	[1]
Charge-offs	1	529
Recoveries	377	166
Net charge-offs (recoveries)	(376)	363
Provision (recovery of provision)	(1,605)	(280)	[1]
Balance at the end of the period	15,451	20,283	[1]
Solar
Changes in allowance for loan and lease losses
Balance at the beginning of the period	5,549	2,745	[1]
Charge-offs	0	0
Recoveries	0	0
Net charge-offs (recoveries)	0	0
Provision (recovery of provision)	209	151	[1]
Balance at the end of the period	5,758	2,896	[1]
Auto and light truck
Changes in allowance for loan and lease losses
Balance at the beginning of the period	28,926	14,400	[1]
Charge-offs	4,286	34
Recoveries	49	82
Net charge-offs (recoveries)	4,237	(48)
Provision (recovery of provision)	4,654	1,023	[1]
Balance at the end of the period	29,343	15,471	[1]
Medium and heavy duty truck
Changes in allowance for loan and lease losses
Balance at the beginning of the period	6,400	4,612	[1]
Charge-offs	0	0
Recoveries	0	0
Net charge-offs (recoveries)	0	0
Provision (recovery of provision)	(129)	(256)	[1]
Balance at the end of the period	6,271	4,356	[1]
Aircraft
Changes in allowance for loan and lease losses
Balance at the beginning of the period	34,053	31,058	[1]
Charge-offs	0	586
Recoveries	119	448
Net charge-offs (recoveries)	(119)	138
Provision (recovery of provision)	1,047	(851)	[1]
Balance at the end of the period	35,219	30,069	[1]
Construction equipment
Changes in allowance for loan and lease losses
Balance at the beginning of the period	19,166	14,120	[1]
Charge-offs	8	1,432
Recoveries	254	211
Net charge-offs (recoveries)	(246)	1,221
Provision (recovery of provision)	(3,103)	9,794	[1]
Balance at the end of the period	16,309	22,693	[1]
Commercial real estate
Changes in allowance for loan and lease losses
Balance at the beginning of the period	22,758	18,350	[1]
Charge-offs	0	1
Recoveries	15	15
Net charge-offs (recoveries)	(15)	(14)
Provision (recovery of provision)	1,561	1,224	[1]
Balance at the end of the period	24,334	19,588	[1]
Residential real estate and home equity
Changes in allowance for loan and lease losses
Balance at the beginning of the period	5,374	3,609	[1]
Charge-offs	5	13
Recoveries	1	27
Net charge-offs (recoveries)	4	(14)
Provision (recovery of provision)	(207)	285	[1]
Balance at the end of the period	5,163	3,908	[1]
Consumer
Changes in allowance for loan and lease losses
Balance at the beginning of the period	1,748	1,434	[1]
Charge-offs	152	243
Recoveries	135	80
Net charge-offs (recoveries)	17	163
Provision (recovery of provision)	(29)	263	[1]
Balance at the end of the period	$ 1,702	$ 1,534	[1]

[1] *ASU 2016-13 adopted during the fourth quarter of 2020 therefore first quarter 2020 amounts reflect the incurred loss method.