Loan and Lease Financings (Details)	9 Months Ended
Sep. 30, 2019 USD ($) item	Dec. 31, 2018 USD ($)
Receivables [Abstract]
Number of methods to assess credit risk \| item	2
Loan and Lease Financings
Recorded investment in loans and leases	$ 5,099,546,000	$ 4,835,464,000
Loan and lease financings excluding residential real estate and consumer loans
Loan and Lease Financings
Recorded investment in loans and leases	4,428,448,000	4,174,972,000
Commercial and agricultural
Loan and Lease Financings
Recorded investment in loans and leases	1,175,936,000	1,073,205,000
Auto and light truck
Loan and Lease Financings
Recorded investment in loans and leases	612,921,000	559,987,000
Medium and heavy duty truck
Loan and Lease Financings
Recorded investment in loans and leases	289,925,000	283,544,000
Aircraft
Loan and Lease Financings
Recorded investment in loans and leases	805,568,000	803,111,000
Construction equipment
Loan and Lease Financings
Recorded investment in loans and leases	685,696,000	645,239,000
Commercial real estate
Loan and Lease Financings
Recorded investment in loans and leases	858,402,000	809,886,000
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	4,290,713,000	4,034,424,000
Credit Quality Grades 1-6 \| Commercial and agricultural
Loan and Lease Financings
Recorded investment in loans and leases	1,123,048,000	1,043,019,000
Credit Quality Grades 1-6 \| Auto and light truck
Loan and Lease Financings
Recorded investment in loans and leases	592,891,000	528,174,000
Credit Quality Grades 1-6 \| Medium and heavy duty truck
Loan and Lease Financings
Recorded investment in loans and leases	288,758,000	281,834,000
Credit Quality Grades 1-6 \| Aircraft
Loan and Lease Financings
Recorded investment in loans and leases	784,453,000	768,442,000
Credit Quality Grades 1-6 \| Construction equipment
Loan and Lease Financings
Recorded investment in loans and leases	658,320,000	625,579,000
Credit Quality Grades 1-6 \| Commercial real estate
Loan and Lease Financings
Recorded investment in loans and leases	843,243,000	787,376,000
Credit Quality Grades 7-12
Loan and Lease Financings
Relationships reviewed quarterly as part of management's evaluation of the appropriateness of the reserve for loan and lease losses	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	137,735,000	140,548,000
Credit Quality Grades 7-12 \| Commercial and agricultural
Loan and Lease Financings
Recorded investment in loans and leases	52,888,000	30,186,000
Credit Quality Grades 7-12 \| Auto and light truck
Loan and Lease Financings
Recorded investment in loans and leases	20,030,000	31,813,000
Credit Quality Grades 7-12 \| Medium and heavy duty truck
Loan and Lease Financings
Recorded investment in loans and leases	1,167,000	1,710,000
Credit Quality Grades 7-12 \| Aircraft
Loan and Lease Financings
Recorded investment in loans and leases	21,115,000	34,669,000
Credit Quality Grades 7-12 \| Construction equipment
Loan and Lease Financings
Recorded investment in loans and leases	27,376,000	19,660,000
Credit Quality Grades 7-12 \| Commercial real estate
Loan and Lease Financings
Recorded investment in loans and leases	$ 15,159,000	$ 22,510,000

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.

+ Details

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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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- Definition

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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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5074-111524

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- References

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