Allowance for Credit Losses (Details) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2021 USD ($) item	Sep. 30, 2020 USD ($)		Sep. 30, 2021 USD ($) item	Sep. 30, 2020 USD ($)
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	$ 136,361	$ 131,283	[1]	$ 140,654	$ 111,254	[2]
Charge-offs	1,077	4,892		6,323	8,342
Recoveries	1,030	1,123		2,610	2,874
Net charge-offs (recoveries)	47	3,769		3,713	5,468
Provision (recovery of provision)	(2,559)	9,303	[1]	(3,186)	31,031	[2]
Balance at the end of the period	133,755	136,817	[1],[2]	133,755	136,817	[1],[2]
Commercial and agricultural
Changes in allowance for loan and lease losses
Balance at the beginning of the period	14,832	25,059	[1]	16,680	20,926	[2]
Charge-offs	21	182		307	753
Recoveries	176	231		694	533
Net charge-offs (recoveries)	(155)	(49)		(387)	220
Provision (recovery of provision)	179	(4,378)	[1]	(1,901)	24	[2]
Balance at the end of the period	15,166	20,730	[1],[2]	15,166	20,730	[1],[2]
Solar
Changes in allowance for loan and lease losses
Balance at the beginning of the period	5,867	3,948	[1]	5,549	2,745	[2]
Charge-offs	0	0		0	0
Recoveries	0	0		0	0
Net charge-offs (recoveries)	0	0		0	0
Provision (recovery of provision)	(15)	392	[1]	303	1,595	[2]
Balance at the end of the period	5,852	4,340	[1],[2]	5,852	4,340	[1],[2]
Auto and light truck
Changes in allowance for loan and lease losses
Balance at the beginning of the period	27,221	17,371	[1]	28,926	14,400	[2]
Charge-offs	407	4,382		5,060	4,416
Recoveries	479	263		664	403
Net charge-offs (recoveries)	(72)	4,119		4,396	4,013
Provision (recovery of provision)	(1,451)	11,997	[1]	1,312	14,862	[2]
Balance at the end of the period	25,842	25,249	[1],[2]	25,842	25,249	[1],[2]
Medium and heavy duty truck
Changes in allowance for loan and lease losses
Balance at the beginning of the period	5,888	4,649	[1]	6,400	4,612	[2]
Charge-offs	0	0		0	0
Recoveries	0	0		0	0
Net charge-offs (recoveries)	0	0		0	0
Provision (recovery of provision)	(158)	(192)	[1]	(670)	(155)	[2]
Balance at the end of the period	5,730	4,457	[1],[2]	5,730	4,457	[1],[2]
Aircraft
Changes in allowance for loan and lease losses
Balance at the beginning of the period	35,301	31,101	[1]	34,053	31,058	[2]
Charge-offs	0	0		0	840
Recoveries	153	191		513	694
Net charge-offs (recoveries)	(153)	(191)		(513)	146
Provision (recovery of provision)	975	953	[1]	1,863	1,333	[2]
Balance at the end of the period	36,429	32,245	[1],[2]	36,429	32,245	[1],[2]
Construction equipment
Changes in allowance for loan and lease losses
Balance at the beginning of the period	17,908	23,872	[1]	19,166	14,120	[2]
Charge-offs	551	21		559	1,582
Recoveries	170	347		424	937
Net charge-offs (recoveries)	381	(326)		135	645
Provision (recovery of provision)	(1,083)	(1,395)	[1]	(2,587)	9,328	[2]
Balance at the end of the period	16,444	22,803	[1],[2]	16,444	22,803	[1],[2]
Commercial real estate
Changes in allowance for loan and lease losses
Balance at the beginning of the period	22,578	19,936	[1]	22,758	18,350	[2]
Charge-offs	0	36		0	37
Recoveries	0	15		19	43
Net charge-offs (recoveries)	0	21		(19)	(6)
Provision (recovery of provision)	(1,253)	1,834	[1]	(1,452)	3,393	[2]
Balance at the end of the period	21,325	21,749	[1],[2]	21,325	21,749	[1],[2]
Residential real estate and home equity
Changes in allowance for loan and lease losses
Balance at the beginning of the period	5,066	3,821	[1]	5,374	3,609	[2]
Charge-offs	0	61		42	74
Recoveries	3	1		14	31
Net charge-offs (recoveries)	(3)	60		28	43
Provision (recovery of provision)	96	(29)	[1]	(181)	166	[2]
Balance at the end of the period	5,165	3,732	[1],[2]	5,165	3,732	[1],[2]
Consumer
Changes in allowance for loan and lease losses
Balance at the beginning of the period	1,700	1,526	[1]	1,748	1,434	[2]
Charge-offs	98	210		355	640
Recoveries	49	75		282	233
Net charge-offs (recoveries)	49	135		73	407
Provision (recovery of provision)	151	121	[1]	127	485	[2]
Balance at the end of the period	$ 1,802	$ 1,512	[1],[2]	$ 1,802	$ 1,512	[1],[2]

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

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