Loans Aging of recorded investment in past due loans (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Accruing Loans 30 to 89 Days Past Due	$ 23,652	$ 21,749
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans	26,364	26,535
Financing Receivable, Recorded Investment, Past Due	50,016	48,284
Financing Receivable, Not Past Due	7,148,422	6,472,341
Loans and Leases Receivable, Recorded Investment	7,198,438	6,520,625
Financing Receivable, 90 Days or More Past Due, Still Accruing	1,594	2,737
financing receivable non accrual current	92,600	66,300
Commercial Financial And Agricultural [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Accruing Loans 30 to 89 Days Past Due	7,372	582
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans	13,968	12,407
Financing Receivable, Recorded Investment, Past Due	21,340	12,989
Financing Receivable, Not Past Due	1,574,177	1,176,514
Loans and Leases Receivable, Recorded Investment	1,595,517	1,189,503
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	28
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Accruing Loans 30 to 89 Days Past Due	82	160
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans	972	1,143
Financing Receivable, Recorded Investment, Past Due	1,054	1,303
Financing Receivable, Not Past Due	1,753,152	1,613,681
Loans and Leases Receivable, Recorded Investment	1,754,206	1,614,984
Financing Receivable, 90 Days or More Past Due, Still Accruing	377	625
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	39
Financing Receivable, Recorded Investment, Past Due	39
Financing Receivable, Not Past Due	227,524	234,463
Loans and Leases Receivable, Recorded Investment	227,563	234,463
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	77	397
Financing Receivable, Recorded Investment, Past Due	77	397
Financing Receivable, Not Past Due	115,647	96,405
Loans and Leases Receivable, Recorded Investment	115,724	96,802
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	0
Construction Real Estate Installment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Accruing Loans 30 to 89 Days Past Due	12	24
Financing Receivable, Recorded Investment, Past Due	12	24
Financing Receivable, Not Past Due	929	1,468
Loans and Leases Receivable, Recorded Investment	941	1,492
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	17
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans	493	908
Financing Receivable, Recorded Investment, Past Due	510	908
Financing Receivable, Not Past Due	526,873	479,512
Loans and Leases Receivable, Recorded Investment	527,383	480,420
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	9,538	12,841
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans	7,814	9,153
Financing Receivable, Recorded Investment, Past Due	17,352	21,994
Financing Receivable, Not Past Due	1,079,953	1,155,703
Loans and Leases Receivable, Recorded Investment	1,097,305	1,177,697
Financing Receivable, 90 Days or More Past Due, Still Accruing	416	1,209
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	805	652
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans	810	779
Financing Receivable, Recorded Investment, Past Due	1,615	1,431
Financing Receivable, Not Past Due	181,060	224,448
Loans and Leases Receivable, Recorded Investment	182,675	225,879
Financing Receivable, 90 Days or More Past Due, Still Accruing	77	44
Residential Real Estate Installment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Accruing Loans 30 to 89 Days Past Due	67	164
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans	71	338
Financing Receivable, Recorded Investment, Past Due	138	502
Financing Receivable, Not Past Due	8,320	12,093
Loans and Leases Receivable, Recorded Investment	8,458	12,595
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	0
Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Accruing Loans 30 to 89 Days Past Due	5,496	6,561
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans	1,213	1,621
Financing Receivable, Recorded Investment, Past Due	6,709	8,182
Financing Receivable, Not Past Due	1,657,505	1,448,507
Loans and Leases Receivable, Recorded Investment	1,664,214	1,456,689
Financing Receivable, 90 Days or More Past Due, Still Accruing	724	645
Leases
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Accruing Loans 30 to 89 Days Past Due	186	368
Financing Receivable Recorded Investment Ninety Days Or More Past Due And Accruing Plus Past Due Nonaccrual Loans	984	186
Financing Receivable, Recorded Investment, Past Due	1,170	554
Financing Receivable, Not Past Due	23,282	29,547
Loans and Leases Receivable, Recorded Investment	24,452	30,101
Financing Receivable, 90 Days or More Past Due, Still Accruing	$ 0	$ 186