Loan and Lease Financings (Details 2)	12 Months Ended
Dec. 31, 2017 USD ($) method	Dec. 31, 2016 USD ($)
Receivables [Abstract]
Number of methods to assess credit risk \| method	2
Loan and Lease Financings
Recorded investment in loans and leases	$ 4,527,678,000	$ 4,188,071,000
Loan and lease financings excluding residential real estate and consumer loans
Loan and Lease Financings
Recorded investment in loans and leases	3,873,410,000	3,536,327,000
Commercial and agricultural
Loan and Lease Financings
Recorded investment in loans and leases	929,997,000	812,264,000
Auto and light truck
Loan and Lease Financings
Recorded investment in loans and leases	496,816,000	411,764,000
Medium and heavy duty truck
Loan and Lease Financings
Recorded investment in loans and leases	296,935,000	294,790,000
Aircraft
Loan and Lease Financings
Recorded investment in loans and leases	844,657,000	802,414,000
Construction equipment
Loan and Lease Financings
Recorded investment in loans and leases	563,437,000	495,925,000
Commercial real estate
Loan and Lease Financings
Recorded investment in loans and leases	741,568,000	719,170,000
Credit Quality Grades 1-6 \| Loan and lease financings excluding residential real estate and consumer loans
Loan and Lease Financings
Recorded investment in loans and leases	3,776,621,000	3,451,277,000
Credit Quality Grades 1-6 \| Commercial and agricultural
Loan and Lease Financings
Recorded investment in loans and leases	906,074,000	784,811,000
Credit Quality Grades 1-6 \| Auto and light truck
Loan and Lease Financings
Recorded investment in loans and leases	482,455,000	407,931,000
Credit Quality Grades 1-6 \| Medium and heavy duty truck
Loan and Lease Financings
Recorded investment in loans and leases	293,318,000	291,558,000
Credit Quality Grades 1-6 \| Aircraft
Loan and Lease Financings
Recorded investment in loans and leases	815,956,000	772,802,000
Credit Quality Grades 1-6 \| Construction equipment
Loan and Lease Financings
Recorded investment in loans and leases	552,684,000	486,923,000
Credit Quality Grades 1-6 \| Commercial real estate
Loan and Lease Financings
Recorded investment in loans and leases	726,134,000	707,252,000
Credit Quality Grades 7-12
Loan and Lease Financings
Threshold value of loan or lease for evaluation of the appropriateness of the impairment reserve	100,000
Credit Quality Grades 7-12 \| Loan and lease financings excluding residential real estate and consumer loans
Loan and Lease Financings
Recorded investment in loans and leases	96,789,000	85,050,000
Credit Quality Grades 7-12 \| Commercial and agricultural
Loan and Lease Financings
Recorded investment in loans and leases	23,923,000	27,453,000
Credit Quality Grades 7-12 \| Auto and light truck
Loan and Lease Financings
Recorded investment in loans and leases	14,361,000	3,833,000
Credit Quality Grades 7-12 \| Medium and heavy duty truck
Loan and Lease Financings
Recorded investment in loans and leases	3,617,000	3,232,000
Credit Quality Grades 7-12 \| Aircraft
Loan and Lease Financings
Recorded investment in loans and leases	28,701,000	29,612,000
Credit Quality Grades 7-12 \| Construction equipment
Loan and Lease Financings
Recorded investment in loans and leases	10,753,000	9,002,000
Credit Quality Grades 7-12 \| Commercial real estate
Loan and Lease Financings
Recorded investment in loans and leases	$ 15,434,000	$ 11,918,000

Represents the amount of loans and leases where the internal credit quality grade is at or below a predetermined classification which are included in comprehensive analysis.

No definition available.

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- Definition

Represents the number of methods to assess credit risk of loans and leases receivables.

+ References

No definition available.

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+ References

No definition available.

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- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524

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