Loans - Impaired Financing Receivables with Related and not Related Allowances (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
With no related allowance recorded:
Average Recorded Investment, Total	$ 17,366	$ 19,491
Interest Income Recognized, Total	157	99
Cash Basis Interest Recognized, Total	157	99
Commercial, industrial, and agricultural
With an allowance recorded:
Average Recorded Investment	2,158	1,884
Interest Income Recognized	38	22
Cash Basis Interest Recognized	38	22
With no related allowance recorded:
Average Recorded Investment	3,376	4,600
Interest Income Recognized	54	46
Cash Basis Interest Recognized	54	46
Commercial mortgages
With an allowance recorded:
Average Recorded Investment	7,267	9,234
Interest Income Recognized	40	18
Cash Basis Interest Recognized	40	18
With no related allowance recorded:
Average Recorded Investment	4,065	3,753
Interest Income Recognized	18	13
Cash Basis Interest Recognized	18	13
Residential real estate
With an allowance recorded:
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Cash Basis Interest Recognized	0	0
With no related allowance recorded:
Average Recorded Investment	500	0
Interest Income Recognized	7	0
Cash Basis Interest Recognized	$ 7	$ 0

Impaired Financing Receivable, Average Recorded Investment With An Allowance Recorded [Abstract]

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- Definition

Impaired Financing Receivable, Average Recorded Investment With No Allowance Recorded [Abstract]

+ References

No definition available.

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- Definition

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5258-111524

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- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

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- Definition

Amount of interest income recognized on a cash-basis method of accounting that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

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Amount of average investment of impaired financing receivables for which there is no related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5258-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

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Amount of interest income, recognized on accrual basis, on financing receivables that are recognized as impaired, for which there is no related allowance for credit losses.

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Amount of interest income, recognized on cash basis, on financing receivables, for which there is no related allowance for credit losses and are recognized as impaired.

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Amount of interest income, recognized on accrual basis, on financing receivables, for which there is a related allowance for credit losses and are recognized as impaired.

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Amount of interest income on financing receivables, for which there is a related allowance for credit losses, recognized on a cash-basis method of accounting that the financing receivables were impaired.

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