Loans Schedule of average recorded investment and interest income recognized on loans individually evaluated for impairment (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	$ 77,491	$ 48,144	$ 56,564
Impaired Financing Receivable, Average Recorded Investment	57,768	51,041	67,070
Impaired Financing Receivable, Interest Income, Cash Basis Method	1,893	1,890	2,708
Commercial Financial And Agricultural [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	33,088	15,120	18,039
Impaired Financing Receivable, Average Recorded Investment	21,415	21,000	23,154
Impaired Financing Receivable, Interest Income, Cash Basis Method	527	695	963
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	41,791	28,426	18,142
Impaired Financing Receivable, Average Recorded Investment	32,132	23,024	21,692
Impaired Financing Receivable, Interest Income, Cash Basis Method	1,241	1,047	903
Construction Real Estate Remaining Commercial [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	453	1,866	1,324
Impaired Financing Receivable, Average Recorded Investment	1,987	1,709	1,729
Impaired Financing Receivable, Interest Income, Cash Basis Method	26	34	64
Residential Real Estate Commercial [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	2,025	2,732	19,059
Impaired Financing Receivable, Average Recorded Investment	2,175	5,308	20,490
Impaired Financing Receivable, Interest Income, Cash Basis Method	99	$ 114	778
Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment			$ 5
Leases
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	134
Impaired Financing Receivable, Average Recorded Investment	$ 59

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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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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.

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+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953550-111524

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