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Related Party Transactions (Details) | 12 Months Ended
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Dec. 31, 2017 USD ($) director | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($)
Loans and Leases Receivable, Related Parties Disclosure [Abstract] |  |  |
Percentage of aircraft owned | 66.00% |  |
Number of directors | director | 5 |  |
Education, Communication, Strategic Enterprise Planning and Corporate Governance Consultation |  |  |
Loans and Leases Receivable, Related Parties Disclosure [Abstract] |  |  |
Aggregate ownership interest of chairman and board of directors | 15.00% |  |
Shareholder |  |  |
Loans and Leases Receivable, Related Parties Disclosure [Abstract] |  |  |
Ownership percentage threshold for related party | 5.00% |  |
Executive Officers, Directors, Shareholders Greater than Five Percent, and Related Entities and Individuals to Such Persons |  |  |
Loans and Leases Receivable, Related Parties Disclosure [Abstract] |  |  |
Loans and leases receivable, related parties | $ 54,600,000 | $ 53,300,000 |
New loans and advances on existing loans | 15,000,000 |  |
Loan repayments | 15,700,000 |  |
Amount of loans removed due to changes in related parties | 2,000,000 |  |
Board of Directors Chairman, Wholly-Owned Entity | Aircraft Usage and Related Activities |  |  |
Loans and Leases Receivable, Related Parties Disclosure [Abstract] |  |  |
Related party transaction, expenses from transactions with related party | 0 | 108,000 | $ 332,000
Related party transactions, other revenues | 0 | 53,000 | 64,000
Board of Directors Chairman | Airplane Usage by Company |  |  |
Loans and Leases Receivable, Related Parties Disclosure [Abstract] |  |  |
Related party transaction, expenses from transactions with related party | 45,000 | 121,000 | 28,000
Related party transactions, other revenues | 17,000 | 19,000 | 23,000
One director and one greater than 10% shareholder | Airplane Usage by Company |  |  |
Loans and Leases Receivable, Related Parties Disclosure [Abstract] |  |  |
Related party transaction, expenses from transactions with related party | 17,000 | 175,000 |
One director and one greater than 10% shareholder | Payment Guarantee |  |  |
Loans and Leases Receivable, Related Parties Disclosure [Abstract] |  |  |
Loans and leases receivable, related parties | 1,900,000 | 2,000,000 |
Entity Majority Owned by Shareholders and Directors | Education, Communication, Strategic Enterprise Planning and Corporate Governance Consultation |  |  |
Loans and Leases Receivable, Related Parties Disclosure [Abstract] |  |  |
Related party transaction, expenses from transactions with related party | $ 73,000 | $ 100,000 | $ 210,000

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