Loans - Impaired Financing Receivables with Related and not Related Allowances (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
With no related allowance recorded:
Average Recorded Investment, Total	$ 15,397	$ 23,224	$ 16,380	$ 21,414
Interest Income Recognized, Total	123	137	383	391
Cash Basis Interest Recognized, Total	123	137	383	391
Commercial, industrial, and agricultural
With an allowance recorded:
Average Recorded Investment	1,480	3,460	1,819	2,672
Interest Income Recognized	32	11	74	54
Cash Basis Interest Recognized	32	11	74	54
With no related allowance recorded:
Average Recorded Investment	3,977	5,569	3,676	5,084
Interest Income Recognized	42	69	128	160
Cash Basis Interest Recognized	42	69	128	160
Commercial mortgages
With an allowance recorded:
Average Recorded Investment	7,024	9,042	7,145	9,147
Interest Income Recognized	12	37	100	111
Cash Basis Interest Recognized	12	37	100	111
With no related allowance recorded:
Average Recorded Investment	2,435	5,153	3,250	4,511
Interest Income Recognized	29	20	62	66
Cash Basis Interest Recognized	29	20	62	66
Residential real estate
With an allowance recorded:
Average Recorded Investment	245	0	122	0
Interest Income Recognized	8	0	8	0
Cash Basis Interest Recognized	8	0	8	0
With no related allowance recorded:
Average Recorded Investment	236	0	368	0
Interest Income Recognized	0	0	11	0
Cash Basis Interest Recognized	$ 0	$ 0	$ 11	$ 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=118936363&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=118936363&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.

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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=118936363&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=118936363&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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