Loan and Lease Financings (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2021 USD ($) class item	Dec. 31, 2020 USD ($)
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	$ 232,440,000	$ 597,450,000
PPP loan balance	443,840,000
PPP loans receivable deferred income	$ 13,620,000
Number of domestic aircraft loan pools | class	2
Amortized cost of loans and leases	$ 5,523,085,000	5,489,301,000
Commercial and agricultural
Loan and Lease Financings
Financing receivable originated during current fiscal year	261,034,000	532,604,000
Financing receivable originated one year prior to current fiscal year	385,520,000	104,819,000
Financing receivable originated two years prior to current fiscal year	92,037,000	118,977,000
Financing receivable originated three years prior to current fiscal year	108,014,000	59,514,000
Financing receivable originated four years prior to current fiscal year	53,633,000	23,223,000
Financing receivable originated five years or more prior to current fiscal year	38,430,000	21,924,000
Revolving Loans	300,040,000	325,057,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	$ 1,238,708,000	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	$ 28,077,000	141,089,000
Financing receivable originated one year prior to current fiscal year	117,313,000	90,435,000
Financing receivable originated two years prior to current fiscal year	89,914,000	20,160,000
Financing receivable originated three years prior to current fiscal year	20,081,000	36,909,000
Financing receivable originated four years prior to current fiscal year	36,740,000	4,011,000
Financing receivable originated five years or more prior to current fiscal year	3,999,000	0
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	296,124,000	292,604,000
Auto and light truck
Loan and Lease Financings
Financing receivable originated during current fiscal year	92,970,000	268,045,000
Financing receivable originated one year prior to current fiscal year	227,427,000	168,977,000
Financing receivable originated two years prior to current fiscal year	144,390,000	65,545,000
Financing receivable originated three years prior to current fiscal year	55,134,000	32,713,000
Financing receivable originated four years prior to current fiscal year	27,402,000	6,460,000
Financing receivable originated five years or more prior to current fiscal year	5,353,000	629,000
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	$ 552,676,000	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	$ 16,870,000	92,698,000
Financing receivable originated one year prior to current fiscal year	86,222,000	89,292,000
Financing receivable originated two years prior to current fiscal year	82,683,000	44,205,000
Financing receivable originated three years prior to current fiscal year	40,273,000	31,773,000
Financing receivable originated four years prior to current fiscal year	26,270,000	16,276,000
Financing receivable originated five years or more prior to current fiscal year	16,318,000	4,928,000
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	$ 268,636,000	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	$ 91,745,000	440,802,000
Financing receivable originated one year prior to current fiscal year	393,745,000	155,919,000
Financing receivable originated two years prior to current fiscal year	146,356,000	93,521,000
Financing receivable originated three years prior to current fiscal year	81,093,000	96,053,000
Financing receivable originated four years prior to current fiscal year	86,350,000	46,159,000
Financing receivable originated five years or more prior to current fiscal year	66,841,000	22,636,000
Revolving Loans	7,640,000	6,370,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	$ 873,770,000	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	$ 59,642,000	328,692,000
Financing receivable originated one year prior to current fiscal year	307,402,000	194,293,000
Financing receivable originated two years prior to current fiscal year	175,285,000	106,962,000
Financing receivable originated three years prior to current fiscal year	93,330,000	43,111,000
Financing receivable originated four years prior to current fiscal year	32,648,000	12,861,000
Financing receivable originated five years or more prior to current fiscal year	14,469,000	5,807,000
Revolving Loans	19,810,000	20,490,000
Revolving Loans Converted to Term	3,158,000	2,672,000
Amortized cost of loans and leases	705,744,000	714,888,000
Commercial real estate
Loan and Lease Financings
Financing receivable originated during current fiscal year	41,131,000	200,243,000
Financing receivable originated one year prior to current fiscal year	200,594,000	212,467,000
Financing receivable originated two years prior to current fiscal year	203,415,000	179,020,000
Financing receivable originated three years prior to current fiscal year	173,858,000	181,693,000
Financing receivable originated four years prior to current fiscal year	176,818,000	70,784,000
Financing receivable originated five years or more prior to current fiscal year	179,064,000	125,284,000
Revolving Loans	503,000	373,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	975,383,000	969,864,000
Residential real estate and home equity
Loan and Lease Financings
Financing receivable originated during current fiscal year	19,235,000	133,829,000
Financing receivable originated one year prior to current fiscal year	130,509,000	65,690,000
Financing receivable originated two years prior to current fiscal year	56,110,000	18,215,000
Financing receivable originated three years prior to current fiscal year	16,861,000	22,943,000
Financing receivable originated four years prior to current fiscal year	17,801,000	41,847,000
Financing receivable originated five years or more prior to current fiscal year	114,208,000	87,541,000
Revolving Loans	126,495,000	135,502,000
Revolving Loans Converted to Term	4,937,000	5,812,000
Amortized cost of loans and leases	486,156,000	511,379,000
Consumer
Loan and Lease Financings
Financing receivable originated during current fiscal year	15,816,000	43,826,000
Financing receivable originated one year prior to current fiscal year	38,546,000	34,508,000
Financing receivable originated two years prior to current fiscal year	29,342,000	18,982,000
Financing receivable originated three years prior to current fiscal year	15,633,000	7,041,000
Financing receivable originated four years prior to current fiscal year	5,637,000	2,267,000
Financing receivable originated five years or more prior to current fiscal year	1,995,000	795,000
Revolving Loans	18,919,000	24,028,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	125,888,000	131,447,000
Credit Quality Grades 1-6 | Commercial and agricultural
Loan and Lease Financings
Financing receivable originated during current fiscal year	255,244,000	525,816,000
Financing receivable originated one year prior to current fiscal year	384,680,000	103,120,000
Financing receivable originated two years prior to current fiscal year	88,262,000	114,251,000
Financing receivable originated three years prior to current fiscal year	103,661,000	56,007,000
Financing receivable originated four years prior to current fiscal year	50,785,000	22,023,000
Financing receivable originated five years or more prior to current fiscal year	35,240,000	19,790,000
Revolving Loans	268,480,000	291,990,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	1,186,352,000	1,132,997,000
Credit Quality Grades 1-6 | Solar
Loan and Lease Financings
Financing receivable originated during current fiscal year	28,077,000	141,089,000
Financing receivable originated one year prior to current fiscal year	116,125,000	90,435,000
Financing receivable originated two years prior to current fiscal year	83,874,000	20,160,000
Financing receivable originated three years prior to current fiscal year	19,336,000	36,909,000
Financing receivable originated four years prior to current fiscal year	36,740,000	4,011,000
Financing receivable originated five years or more prior to current fiscal year	3,999,000	0
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	288,151,000	292,604,000
Credit Quality Grades 1-6 | Auto and light truck
Loan and Lease Financings
Financing receivable originated during current fiscal year	92,970,000	248,932,000
Financing receivable originated one year prior to current fiscal year	209,596,000	141,841,000
Financing receivable originated two years prior to current fiscal year	119,507,000	52,749,000
Financing receivable originated three years prior to current fiscal year	44,072,000	24,101,000
Financing receivable originated four years prior to current fiscal year	19,813,000	4,210,000
Financing receivable originated five years or more prior to current fiscal year	3,384,000	608,000
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	489,342,000	472,441,000
Credit Quality Grades 1-6 | Medium and heavy duty truck
Loan and Lease Financings
Financing receivable originated during current fiscal year	16,870,000	92,698,000
Financing receivable originated one year prior to current fiscal year	86,222,000	88,314,000
Financing receivable originated two years prior to current fiscal year	81,785,000	44,205,000
Financing receivable originated three years prior to current fiscal year	40,273,000	31,773,000
Financing receivable originated four years prior to current fiscal year	26,270,000	15,644,000
Financing receivable originated five years or more prior to current fiscal year	15,702,000	4,840,000
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	267,122,000	277,474,000
Credit Quality Grades 1-6 | Aircraft
Loan and Lease Financings
Financing receivable originated during current fiscal year	91,745,000	429,283,000
Financing receivable originated one year prior to current fiscal year	383,028,000	153,358,000
Financing receivable originated two years prior to current fiscal year	143,854,000	93,042,000
Financing receivable originated three years prior to current fiscal year	80,623,000	95,457,000
Financing receivable originated four years prior to current fiscal year	85,767,000	43,972,000
Financing receivable originated five years or more prior to current fiscal year	63,229,000	20,966,000
Revolving Loans	7,640,000	6,370,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	855,886,000	842,448,000
Credit Quality Grades 1-6 | Construction equipment
Loan and Lease Financings
Financing receivable originated during current fiscal year	59,070,000	311,174,000
Financing receivable originated one year prior to current fiscal year	295,555,000	180,550,000
Financing receivable originated two years prior to current fiscal year	167,247,000	96,320,000
Financing receivable originated three years prior to current fiscal year	85,951,000	42,713,000
Financing receivable originated four years prior to current fiscal year	32,604,000	12,624,000
Financing receivable originated five years or more prior to current fiscal year	14,310,000	5,722,000
Revolving Loans	18,105,000	17,502,000
Revolving Loans Converted to Term	41,000	737,000
Amortized cost of loans and leases	672,883,000	667,342,000
Credit Quality Grades 1-6 | Commercial real estate
Loan and Lease Financings
Financing receivable originated during current fiscal year	37,606,000	190,725,000
Financing receivable originated one year prior to current fiscal year	192,699,000	204,477,000
Financing receivable originated two years prior to current fiscal year	195,889,000	173,847,000
Financing receivable originated three years prior to current fiscal year	169,354,000	175,009,000
Financing receivable originated four years prior to current fiscal year	170,139,000	69,022,000
Financing receivable originated five years or more prior to current fiscal year	175,081,000	122,762,000
Revolving Loans	503,000	373,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	941,271,000	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	100,000
Credit Quality Grades 7-12 | Commercial and agricultural
Loan and Lease Financings
Financing receivable originated during current fiscal year	5,790,000	6,788,000
Financing receivable originated one year prior to current fiscal year	840,000	1,699,000
Financing receivable originated two years prior to current fiscal year	3,775,000	4,726,000
Financing receivable originated three years prior to current fiscal year	4,353,000	3,507,000
Financing receivable originated four years prior to current fiscal year	2,848,000	1,200,000
Financing receivable originated five years or more prior to current fiscal year	3,190,000	2,134,000
Revolving Loans	31,560,000	33,067,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	52,356,000	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	1,188,000	0
Financing receivable originated two years prior to current fiscal year	6,040,000	0
Financing receivable originated three years prior to current fiscal year	745,000	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	7,973,000	0
Credit Quality Grades 7-12 | Auto and light truck
Loan and Lease Financings
Financing receivable originated during current fiscal year	0	19,113,000
Financing receivable originated one year prior to current fiscal year	17,831,000	27,136,000
Financing receivable originated two years prior to current fiscal year	24,883,000	12,796,000
Financing receivable originated three years prior to current fiscal year	11,062,000	8,612,000
Financing receivable originated four years prior to current fiscal year	7,589,000	2,250,000
Financing receivable originated five years or more prior to current fiscal year	1,969,000	21,000
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	63,334,000	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	898,000	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	616,000	88,000
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	1,514,000	1,698,000
Credit Quality Grades 7-12 | Aircraft
Loan and Lease Financings
Financing receivable originated during current fiscal year	0	11,519,000
Financing receivable originated one year prior to current fiscal year	10,717,000	2,561,000
Financing receivable originated two years prior to current fiscal year	2,502,000	479,000
Financing receivable originated three years prior to current fiscal year	470,000	596,000
Financing receivable originated four years prior to current fiscal year	583,000	2,187,000
Financing receivable originated five years or more prior to current fiscal year	3,612,000	1,670,000
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	17,884,000	19,012,000
Credit Quality Grades 7-12 | Construction equipment
Loan and Lease Financings
Financing receivable originated during current fiscal year	572,000	17,518,000
Financing receivable originated one year prior to current fiscal year	11,847,000	13,743,000
Financing receivable originated two years prior to current fiscal year	8,038,000	10,642,000
Financing receivable originated three years prior to current fiscal year	7,379,000	398,000
Financing receivable originated four years prior to current fiscal year	44,000	237,000
Financing receivable originated five years or more prior to current fiscal year	159,000	85,000
Revolving Loans	1,705,000	2,988,000
Revolving Loans Converted to Term	3,117,000	1,935,000
Amortized cost of loans and leases	32,861,000	47,546,000
Credit Quality Grades 7-12 | Commercial real estate
Loan and Lease Financings
Financing receivable originated during current fiscal year	3,525,000	9,518,000
Financing receivable originated one year prior to current fiscal year	7,895,000	7,990,000
Financing receivable originated two years prior to current fiscal year	7,526,000	5,173,000
Financing receivable originated three years prior to current fiscal year	4,504,000	6,684,000
Financing receivable originated four years prior to current fiscal year	6,679,000	1,762,000
Financing receivable originated five years or more prior to current fiscal year	3,983,000	2,522,000
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	34,112,000	33,649,000
Performing | Residential real estate and home equity
Loan and Lease Financings
Financing receivable originated during current fiscal year	19,235,000	133,829,000
Financing receivable originated one year prior to current fiscal year	130,509,000	65,690,000
Financing receivable originated two years prior to current fiscal year	56,110,000	18,194,000
Financing receivable originated three years prior to current fiscal year	16,840,000	22,929,000
Financing receivable originated four years prior to current fiscal year	17,801,000	41,847,000
Financing receivable originated five years or more prior to current fiscal year	112,867,000	86,106,000
Revolving Loans	126,248,000	135,255,000
Revolving Loans Converted to Term	4,837,000	5,703,000
Amortized cost of loans and leases	484,447,000	509,553,000
Performing | Consumer
Loan and Lease Financings
Financing receivable originated during current fiscal year	15,816,000	43,824,000
Financing receivable originated one year prior to current fiscal year	38,546,000	34,409,000
Financing receivable originated two years prior to current fiscal year	29,303,000	18,904,000
Financing receivable originated three years prior to current fiscal year	15,557,000	7,005,000
Financing receivable originated four years prior to current fiscal year	5,605,000	2,259,000
Financing receivable originated five years or more prior to current fiscal year	1,987,000	793,000
Revolving Loans	18,761,000	23,869,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	$ 125,575,000	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	21,000	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	1,341,000	1,435,000
Revolving Loans	247,000	247,000
Revolving Loans Converted to Term	100,000	109,000
Amortized cost of loans and leases	1,709,000	1,826,000
Nonperforming | Consumer
Loan and Lease Financings
Financing receivable originated during current fiscal year	0	2,000
Financing receivable originated one year prior to current fiscal year	0	99,000
Financing receivable originated two years prior to current fiscal year	39,000	78,000
Financing receivable originated three years prior to current fiscal year	76,000	36,000
Financing receivable originated four years prior to current fiscal year	32,000	8,000
Financing receivable originated five years or more prior to current fiscal year	8,000	2,000
Revolving Loans	158,000	159,000
Revolving Loans Converted to Term	0	0
Amortized cost of loans and leases	$ 313,000	$ 384,000