Loans Aging of recorded investment in past due loans (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Accruing Loans 30 to 89 Days Past Due	$ 21,749	$ 29,919
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans	26,535	19,602
Financing Receivable, Recorded Investment, Past Due	48,284	49,521
Financing Receivable, Not Past Due	6,472,341	5,660,277
Loans and Leases Receivable, Recorded Investment	6,520,625	5,709,798
Financing Receivable, 90 Days or More Past Due, Still Accruing	2,737	2,302
financing receivable non accrual current	66,300	50,700
Commercial Financial And Agricultural [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Accruing Loans 30 to 89 Days Past Due	582	4,786
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans	12,407	1,375
Financing Receivable, Recorded Investment, Past Due	12,989	6,161
Financing Receivable, Not Past Due	1,176,514	1,071,228
Loans and Leases Receivable, Recorded Investment	1,189,503	1,077,389
Financing Receivable, 90 Days or More Past Due, Still Accruing	28	10
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Accruing Loans 30 to 89 Days Past Due	160	780
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans	1,143	3,584
Financing Receivable, Recorded Investment, Past Due	1,303	4,364
Financing Receivable, Not Past Due	1,613,681	1,283,431
Loans and Leases Receivable, Recorded Investment	1,614,984	1,287,795
Financing Receivable, 90 Days or More Past Due, Still Accruing	625	0
Construction Real Estate Remaining Commercial [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans		1,635
Financing Receivable, Recorded Investment, Past Due		1,635
Financing Receivable, Not Past Due	234,463	174,466
Loans and Leases Receivable, Recorded Investment	234,463	176,101
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	0
Construction Real Estate Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Accruing Loans 30 to 89 Days Past Due	397	133
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans		20
Financing Receivable, Recorded Investment, Past Due	397	153
Financing Receivable, Not Past Due	96,405	70,539
Loans and Leases Receivable, Recorded Investment	96,802	70,692
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	20
Construction Real Estate Installment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Accruing Loans 30 to 89 Days Past Due	24	28
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans		19
Financing Receivable, Recorded Investment, Past Due	24	47
Financing Receivable, Not Past Due	1,468	2,393
Loans and Leases Receivable, Recorded Investment	1,492	2,440
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	0
Residential Real Estate Commercial [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Accruing Loans 30 to 89 Days Past Due		683
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans	908	1,104
Financing Receivable, Recorded Investment, Past Due	908	1,787
Financing Receivable, Not Past Due	479,512	429,093
Loans and Leases Receivable, Recorded Investment	480,420	430,880
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	0
Residential Real Estate Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Accruing Loans 30 to 89 Days Past Due	12,841	13,210
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans	9,153	8,553
Financing Receivable, Recorded Investment, Past Due	21,994	21,763
Financing Receivable, Not Past Due	1,155,703	1,113,742
Loans and Leases Receivable, Recorded Investment	1,177,697	1,135,505
Financing Receivable, 90 Days or More Past Due, Still Accruing	1,209	1,124
Residential Real Estate Home Equity Line Of Credit [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Accruing Loans 30 to 89 Days Past Due	652	620
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans	779	907
Financing Receivable, Recorded Investment, Past Due	1,431	1,527
Financing Receivable, Not Past Due	224,448	214,915
Loans and Leases Receivable, Recorded Investment	225,879	216,442
Financing Receivable, 90 Days or More Past Due, Still Accruing	44	9
Residential Real Estate Installment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Accruing Loans 30 to 89 Days Past Due	164	155
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans	338	274
Financing Receivable, Recorded Investment, Past Due	502	429
Financing Receivable, Not Past Due	12,093	13,934
Loans and Leases Receivable, Recorded Investment	12,595	14,363
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	24
Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Accruing Loans 30 to 89 Days Past Due	6,561	9,524
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans	1,621	2,131
Financing Receivable, Recorded Investment, Past Due	8,182	11,655
Financing Receivable, Not Past Due	1,448,507	1,284,237
Loans and Leases Receivable, Recorded Investment	1,456,689	1,295,892
Financing Receivable, 90 Days or More Past Due, Still Accruing	645	1,115
Leases
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Accruing Loans 30 to 89 Days Past Due	368
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans	186
Financing Receivable, Recorded Investment, Past Due	554
Financing Receivable, Not Past Due	29,547	2,299
Loans and Leases Receivable, Recorded Investment	30,101	2,299
Financing Receivable, 90 Days or More Past Due, Still Accruing	$ 186	$ 0