Loan and Lease Financings (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2021 USD ($) item class	Dec. 31, 2020 USD ($)
Receivables [Abstract]
Number of methods to assess credit risk | item	2
Loan and Lease Financings
Number of methods to assess credit risk | item	2
PPP loan originations	$ 261,460,000	$ 597,450,000
PPP loan balance	171,620,000
PPP loans receivable deferred income	$ 6,280,000
Number of domestic aircraft loan pools | class	2
Amortized cost of loans and leases	$ 5,358,797,000	5,489,301,000
Commercial and agricultural
Loan and Lease Financings
Financing receivable originated during current fiscal year	264,020,000	532,604,000
Financing receivable originated one year prior to current fiscal year	164,295,000	104,819,000
Financing receivable originated two years prior to current fiscal year	72,405,000	118,977,000
Financing receivable originated three years prior to current fiscal year	68,559,000	59,514,000
Financing receivable originated four years prior to current fiscal year	40,269,000	23,223,000
Financing receivable originated five years or more prior to current fiscal year	23,404,000	21,924,000
Revolving Loans	372,897,000	325,057,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	$ 1,005,849,000	1,186,118,000
Commercial and agricultural | Minimum
Loan and Lease Financings
Expected life of underlying collateral	3 years
Commercial and agricultural | Maximum
Loan and Lease Financings
Expected life of underlying collateral	7 years
Solar
Loan and Lease Financings
Financing receivable originated during current fiscal year	$ 95,941,000	141,089,000
Financing receivable originated one year prior to current fiscal year	61,135,000	90,435,000
Financing receivable originated two years prior to current fiscal year	87,761,000	20,160,000
Financing receivable originated three years prior to current fiscal year	19,815,000	36,909,000
Financing receivable originated four years prior to current fiscal year	35,536,000	4,011,000
Financing receivable originated five years or more prior to current fiscal year	3,807,000	0
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	303,995,000	292,604,000
Auto and light truck
Loan and Lease Financings
Financing receivable originated during current fiscal year	281,269,000	268,045,000
Financing receivable originated one year prior to current fiscal year	166,643,000	168,977,000
Financing receivable originated two years prior to current fiscal year	98,451,000	65,545,000
Financing receivable originated three years prior to current fiscal year	36,068,000	32,713,000
Financing receivable originated four years prior to current fiscal year	20,119,000	6,460,000
Financing receivable originated five years or more prior to current fiscal year	2,708,000	629,000
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	$ 605,258,000	542,369,000
Auto and light truck | Minimum
Loan and Lease Financings
Loan amortization period	18 months
Direct finance lease term	3 years
Auto and light truck | Maximum
Loan and Lease Financings
Loan amortization period	4 years
Direct finance lease term	7 years
Medium and heavy duty truck
Loan and Lease Financings
Financing receivable originated during current fiscal year	$ 49,844,000	92,698,000
Financing receivable originated one year prior to current fiscal year	74,581,000	89,292,000
Financing receivable originated two years prior to current fiscal year	69,054,000	44,205,000
Financing receivable originated three years prior to current fiscal year	28,790,000	31,773,000
Financing receivable originated four years prior to current fiscal year	17,651,000	16,276,000
Financing receivable originated five years or more prior to current fiscal year	8,684,000	4,928,000
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	$ 248,604,000	279,172,000
Medium and heavy duty truck | Minimum
Loan and Lease Financings
Period of amortization to reach equity position in collateral	3 years
Medium and heavy duty truck | Maximum
Loan and Lease Financings
Period of amortization to reach equity position in collateral	4 years
Aircraft
Loan and Lease Financings
Financing receivable originated during current fiscal year	$ 310,355,000	440,802,000
Financing receivable originated one year prior to current fiscal year	317,606,000	155,919,000
Financing receivable originated two years prior to current fiscal year	104,713,000	93,521,000
Financing receivable originated three years prior to current fiscal year	57,590,000	96,053,000
Financing receivable originated four years prior to current fiscal year	62,910,000	46,159,000
Financing receivable originated five years or more prior to current fiscal year	39,095,000	22,636,000
Revolving Loans	7,808,000	6,370,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	$ 900,077,000	861,460,000
Aircraft | Minimum
Loan and Lease Financings
Loan amortization period	10 years
Aircraft | Maximum
Loan and Lease Financings
Loan amortization period	15 years
Construction equipment
Loan and Lease Financings
Financing receivable originated during current fiscal year	$ 256,133,000	328,692,000
Financing receivable originated one year prior to current fiscal year	233,689,000	194,293,000
Financing receivable originated two years prior to current fiscal year	130,099,000	106,962,000
Financing receivable originated three years prior to current fiscal year	58,689,000	43,111,000
Financing receivable originated four years prior to current fiscal year	20,225,000	12,861,000
Financing receivable originated five years or more prior to current fiscal year	6,609,000	5,807,000
Revolving Loans	17,068,000	20,490,000
Revolving Loans Converted to Term	6,900,000	2,672,000
Amortized cost of loans and leases	729,412,000	714,888,000
Commercial real estate
Loan and Lease Financings
Financing receivable originated during current fiscal year	135,682,000	200,243,000
Financing receivable originated one year prior to current fiscal year	197,256,000	212,467,000
Financing receivable originated two years prior to current fiscal year	176,177,000	179,020,000
Financing receivable originated three years prior to current fiscal year	146,737,000	181,693,000
Financing receivable originated four years prior to current fiscal year	157,302,000	70,784,000
Financing receivable originated five years or more prior to current fiscal year	125,452,000	125,284,000
Revolving Loans	525,000	373,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	939,131,000	969,864,000
Residential real estate and home equity
Loan and Lease Financings
Financing receivable originated during current fiscal year	72,849,000	133,829,000
Financing receivable originated one year prior to current fiscal year	119,749,000	65,690,000
Financing receivable originated two years prior to current fiscal year	46,096,000	18,215,000
Financing receivable originated three years prior to current fiscal year	13,632,000	22,943,000
Financing receivable originated four years prior to current fiscal year	13,736,000	41,847,000
Financing receivable originated five years or more prior to current fiscal year	98,655,000	87,541,000
Revolving Loans	123,085,000	135,502,000
Revolving Loans Converted to Term	5,091,000	5,812,000
Amortized cost of loans and leases	492,893,000	511,379,000
Consumer
Loan and Lease Financings
Financing receivable originated during current fiscal year	47,527,000	43,826,000
Financing receivable originated one year prior to current fiscal year	28,530,000	34,508,000
Financing receivable originated two years prior to current fiscal year	20,581,000	18,982,000
Financing receivable originated three years prior to current fiscal year	10,250,000	7,041,000
Financing receivable originated four years prior to current fiscal year	3,327,000	2,267,000
Financing receivable originated five years or more prior to current fiscal year	927,000	795,000
Revolving Loans	22,436,000	24,028,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	133,578,000	131,447,000
Credit Quality Grades 1-6 | Commercial and agricultural
Loan and Lease Financings
Financing receivable originated during current fiscal year	259,015,000	525,816,000
Financing receivable originated one year prior to current fiscal year	164,059,000	103,120,000
Financing receivable originated two years prior to current fiscal year	69,021,000	114,251,000
Financing receivable originated three years prior to current fiscal year	65,697,000	56,007,000
Financing receivable originated four years prior to current fiscal year	38,019,000	22,023,000
Financing receivable originated five years or more prior to current fiscal year	22,880,000	19,790,000
Revolving Loans	352,797,000	291,990,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	971,488,000	1,132,997,000
Credit Quality Grades 1-6 | Solar
Loan and Lease Financings
Financing receivable originated during current fiscal year	95,941,000	141,089,000
Financing receivable originated one year prior to current fiscal year	59,984,000	90,435,000
Financing receivable originated two years prior to current fiscal year	81,811,000	20,160,000
Financing receivable originated three years prior to current fiscal year	19,084,000	36,909,000
Financing receivable originated four years prior to current fiscal year	35,536,000	4,011,000
Financing receivable originated five years or more prior to current fiscal year	3,807,000	0
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	296,163,000	292,604,000
Credit Quality Grades 1-6 | Auto and light truck
Loan and Lease Financings
Financing receivable originated during current fiscal year	273,260,000	248,932,000
Financing receivable originated one year prior to current fiscal year	150,752,000	141,841,000
Financing receivable originated two years prior to current fiscal year	89,456,000	52,749,000
Financing receivable originated three years prior to current fiscal year	30,896,000	24,101,000
Financing receivable originated four years prior to current fiscal year	14,202,000	4,210,000
Financing receivable originated five years or more prior to current fiscal year	1,498,000	608,000
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	560,064,000	472,441,000
Credit Quality Grades 1-6 | Medium and heavy duty truck
Loan and Lease Financings
Financing receivable originated during current fiscal year	49,844,000	92,698,000
Financing receivable originated one year prior to current fiscal year	74,581,000	88,314,000
Financing receivable originated two years prior to current fiscal year	69,054,000	44,205,000
Financing receivable originated three years prior to current fiscal year	28,790,000	31,773,000
Financing receivable originated four years prior to current fiscal year	17,651,000	15,644,000
Financing receivable originated five years or more prior to current fiscal year	8,363,000	4,840,000
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	248,283,000	277,474,000
Credit Quality Grades 1-6 | Aircraft
Loan and Lease Financings
Financing receivable originated during current fiscal year	309,624,000	429,283,000
Financing receivable originated one year prior to current fiscal year	316,914,000	153,358,000
Financing receivable originated two years prior to current fiscal year	104,713,000	93,042,000
Financing receivable originated three years prior to current fiscal year	56,148,000	95,457,000
Financing receivable originated four years prior to current fiscal year	62,412,000	43,972,000
Financing receivable originated five years or more prior to current fiscal year	36,119,000	20,966,000
Revolving Loans	7,308,000	6,370,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	893,238,000	842,448,000
Credit Quality Grades 1-6 | Construction equipment
Loan and Lease Financings
Financing receivable originated during current fiscal year	227,587,000	311,174,000
Financing receivable originated one year prior to current fiscal year	224,825,000	180,550,000
Financing receivable originated two years prior to current fiscal year	125,132,000	96,320,000
Financing receivable originated three years prior to current fiscal year	57,157,000	42,713,000
Financing receivable originated four years prior to current fiscal year	19,888,000	12,624,000
Financing receivable originated five years or more prior to current fiscal year	6,548,000	5,722,000
Revolving Loans	16,316,000	17,502,000
Revolving Loans Converted to Term	3,797,000	737,000
Amortized cost of loans and leases	681,250,000	667,342,000
Credit Quality Grades 1-6 | Commercial real estate
Loan and Lease Financings
Financing receivable originated during current fiscal year	133,207,000	190,725,000
Financing receivable originated one year prior to current fiscal year	191,237,000	204,477,000
Financing receivable originated two years prior to current fiscal year	170,497,000	173,847,000
Financing receivable originated three years prior to current fiscal year	146,222,000	175,009,000
Financing receivable originated four years prior to current fiscal year	151,008,000	69,022,000
Financing receivable originated five years or more prior to current fiscal year	123,105,000	122,762,000
Revolving Loans	525,000	373,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	915,801,000	936,215,000
Credit Quality Grades 7-12
Loan and Lease Financings
Relationships reviewed quarterly as part of management's evaluation of the appropriateness of the allowance for loan and lease losses	250,000
Credit Quality Grades 7-12 | Commercial and agricultural
Loan and Lease Financings
Financing receivable originated during current fiscal year	5,005,000	6,788,000
Financing receivable originated one year prior to current fiscal year	236,000	1,699,000
Financing receivable originated two years prior to current fiscal year	3,384,000	4,726,000
Financing receivable originated three years prior to current fiscal year	2,862,000	3,507,000
Financing receivable originated four years prior to current fiscal year	2,250,000	1,200,000
Financing receivable originated five years or more prior to current fiscal year	524,000	2,134,000
Revolving Loans	20,100,000	33,067,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	34,361,000	53,121,000
Credit Quality Grades 7-12 | Solar
Loan and Lease Financings
Financing receivable originated during current fiscal year	0	0
Financing receivable originated one year prior to current fiscal year	1,151,000	0
Financing receivable originated two years prior to current fiscal year	5,950,000	0
Financing receivable originated three years prior to current fiscal year	731,000	0
Financing receivable originated four years prior to current fiscal year	0	0
Financing receivable originated five years or more prior to current fiscal year	0	0
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	7,832,000	0
Credit Quality Grades 7-12 | Auto and light truck
Loan and Lease Financings
Financing receivable originated during current fiscal year	8,009,000	19,113,000
Financing receivable originated one year prior to current fiscal year	15,891,000	27,136,000
Financing receivable originated two years prior to current fiscal year	8,995,000	12,796,000
Financing receivable originated three years prior to current fiscal year	5,172,000	8,612,000
Financing receivable originated four years prior to current fiscal year	5,917,000	2,250,000
Financing receivable originated five years or more prior to current fiscal year	1,210,000	21,000
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	45,194,000	69,928,000
Credit Quality Grades 7-12 | Medium and heavy duty truck
Loan and Lease Financings
Financing receivable originated during current fiscal year	0	0
Financing receivable originated one year prior to current fiscal year	0	978,000
Financing receivable originated two years prior to current fiscal year	0	0
Financing receivable originated three years prior to current fiscal year	0	0
Financing receivable originated four years prior to current fiscal year	0	632,000
Financing receivable originated five years or more prior to current fiscal year	321,000	88,000
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	321,000	1,698,000
Credit Quality Grades 7-12 | Aircraft
Loan and Lease Financings
Financing receivable originated during current fiscal year	731,000	11,519,000
Financing receivable originated one year prior to current fiscal year	692,000	2,561,000
Financing receivable originated two years prior to current fiscal year	0	479,000
Financing receivable originated three years prior to current fiscal year	1,442,000	596,000
Financing receivable originated four years prior to current fiscal year	498,000	2,187,000
Financing receivable originated five years or more prior to current fiscal year	2,976,000	1,670,000
Revolving Loans	500,000	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	6,839,000	19,012,000
Credit Quality Grades 7-12 | Construction equipment
Loan and Lease Financings
Financing receivable originated during current fiscal year	28,546,000	17,518,000
Financing receivable originated one year prior to current fiscal year	8,864,000	13,743,000
Financing receivable originated two years prior to current fiscal year	4,967,000	10,642,000
Financing receivable originated three years prior to current fiscal year	1,532,000	398,000
Financing receivable originated four years prior to current fiscal year	337,000	237,000
Financing receivable originated five years or more prior to current fiscal year	61,000	85,000
Revolving Loans	752,000	2,988,000
Revolving Loans Converted to Term	3,103,000	1,935,000
Amortized cost of loans and leases	48,162,000	47,546,000
Credit Quality Grades 7-12 | Commercial real estate
Loan and Lease Financings
Financing receivable originated during current fiscal year	2,475,000	9,518,000
Financing receivable originated one year prior to current fiscal year	6,019,000	7,990,000
Financing receivable originated two years prior to current fiscal year	5,680,000	5,173,000
Financing receivable originated three years prior to current fiscal year	515,000	6,684,000
Financing receivable originated four years prior to current fiscal year	6,294,000	1,762,000
Financing receivable originated five years or more prior to current fiscal year	2,347,000	2,522,000
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	23,330,000	33,649,000
Performing | Residential real estate and home equity
Loan and Lease Financings
Financing receivable originated during current fiscal year	72,849,000	133,829,000
Financing receivable originated one year prior to current fiscal year	119,749,000	65,690,000
Financing receivable originated two years prior to current fiscal year	46,096,000	18,194,000
Financing receivable originated three years prior to current fiscal year	13,632,000	22,929,000
Financing receivable originated four years prior to current fiscal year	13,736,000	41,847,000
Financing receivable originated five years or more prior to current fiscal year	97,876,000	86,106,000
Revolving Loans	122,849,000	135,255,000
Revolving Loans Converted to Term	5,008,000	5,703,000
Amortized cost of loans and leases	491,795,000	509,553,000
Performing | Consumer
Loan and Lease Financings
Financing receivable originated during current fiscal year	47,476,000	43,824,000
Financing receivable originated one year prior to current fiscal year	28,490,000	34,409,000
Financing receivable originated two years prior to current fiscal year	20,519,000	18,904,000
Financing receivable originated three years prior to current fiscal year	10,204,000	7,005,000
Financing receivable originated four years prior to current fiscal year	3,084,000	2,259,000
Financing receivable originated five years or more prior to current fiscal year	922,000	793,000
Revolving Loans	22,436,000	23,869,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	$ 133,131,000	131,063,000
Nonperforming
Loan and Lease Financings
Classification of nonperforming loans, threshold period past due	90 days
Nonperforming | Residential real estate and home equity
Loan and Lease Financings
Financing receivable originated during current fiscal year	$ 0	0
Financing receivable originated one year prior to current fiscal year	0	0
Financing receivable originated two years prior to current fiscal year	0	21,000
Financing receivable originated three years prior to current fiscal year	0	14,000
Financing receivable originated four years prior to current fiscal year	0	0
Financing receivable originated five years or more prior to current fiscal year	779,000	1,435,000
Revolving Loans	236,000	247,000
Revolving Loans Converted to Term	83,000	109,000
Amortized cost of loans and leases	1,098,000	1,826,000
Nonperforming | Consumer
Loan and Lease Financings
Financing receivable originated during current fiscal year	51,000	2,000
Financing receivable originated one year prior to current fiscal year	40,000	99,000
Financing receivable originated two years prior to current fiscal year	62,000	78,000
Financing receivable originated three years prior to current fiscal year	46,000	36,000
Financing receivable originated four years prior to current fiscal year	243,000	8,000
Financing receivable originated five years or more prior to current fiscal year	5,000	2,000
Revolving Loans	0	159,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	$ 447,000	$ 384,000