Loans and Asset Quality Information (Schedule of Analysis of Payment Status of Loans) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	$ 31,656	$ 24,866
Accruing Current	4,782,158	4,402,978
Loans, gross	4,819,175	4,451,525	$ 4,394,984
Unamortized net deferred loan costs (fees)	(5,439)	1,941	1,560
Total loans	4,813,736	4,453,466	4,396,544
Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	3,049	17,236
Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	1,513	5,683
Accruing 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	799	762
PCI Loans
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	0	0
Accruing Current	8,804	11,646
Loans, gross	9,616	12,664
PCI Loans | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	0	218
PCI Loans | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	13	38
PCI Loans | Accruing 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	799	762
Commercial, financial, and agricultural
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	8,473	5,518
Accruing Current	795,437	497,788
Loans, gross	804,831	504,271	486,768
Commercial, financial, and agricultural | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	629	752
Commercial, financial, and agricultural | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	116	0
Commercial, financial, and agricultural | Accruing 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	0	0
Real estate, commercial | Real estate – construction, land development & other land loans
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	872	1,067
Accruing Current	652,057	529,444
Loans, gross	653,120	530,866	471,326
Real estate, commercial | Real estate – construction, land development & other land loans | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	41	37
Real estate, commercial | Real estate – construction, land development & other land loans | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	0	152
Real estate, commercial | Real estate – construction, land development & other land loans | Accruing 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	0	0
Real estate, commercial | Real estate – mortgage – commercial and other
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	14,795	8,820
Accruing Current	1,964,390	1,897,573
Loans, gross	1,983,622	1,917,280	1,928,931
Real estate, commercial | Real estate – mortgage – commercial and other | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	466	4,257
Real estate, commercial | Real estate – mortgage – commercial and other | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	0	0
Real estate, commercial | Real estate – mortgage – commercial and other | Accruing 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	0	0
Real estate, mortgage | Real estate – mortgage – residential (1-4 family) first mortgages
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	5,742	7,552
Accruing Current	1,003,741	1,076,205
Loans, gross	1,017,087	1,105,014	1,093,619
Real estate, mortgage | Real estate – mortgage – residential (1-4 family) first mortgages | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	1,122	10,858
Real estate, mortgage | Real estate – mortgage – residential (1-4 family) first mortgages | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	1,307	5,056
Real estate, mortgage | Real estate – mortgage – residential (1-4 family) first mortgages | Accruing 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	0	0
Real estate, mortgage | Real estate – mortgage – home equity loans / lines of credit
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	1,594	1,797
Accruing Current	307,918	334,832
Loans, gross	310,326	337,922	343,378
Real estate, mortgage | Real estate – mortgage – home equity loans / lines of credit | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	678	770
Real estate, mortgage | Real estate – mortgage – home equity loans / lines of credit | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	40	300
Real estate, mortgage | Real estate – mortgage – home equity loans / lines of credit | Accruing 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	0	0
Consumer loans
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	180	112
Accruing Current	49,811	55,490
Loans, gross	50,189	56,172	$ 70,962
Consumer loans | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	113	344
Consumer loans | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	37	137
Consumer loans | Accruing 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	0	0
Loans, Excluding Purchased Credit Impaired Loans | Commercial, financial, and agricultural
Financing Receivable, Past Due [Line Items]
Loans, gross	804,655	504,058
Loans, Excluding Purchased Credit Impaired Loans | Real estate, commercial | Real estate – construction, land development & other land loans
Financing Receivable, Past Due [Line Items]
Loans, gross	652,970	530,700
Loans, Excluding Purchased Credit Impaired Loans | Real estate, commercial | Real estate – mortgage – commercial and other
Financing Receivable, Past Due [Line Items]
Loans, gross	1,979,651	1,910,650
Loans, Excluding Purchased Credit Impaired Loans | Real estate, mortgage | Real estate – mortgage – residential (1-4 family) first mortgages
Financing Receivable, Past Due [Line Items]
Loans, gross	1,011,912	1,099,671
Loans, Excluding Purchased Credit Impaired Loans | Real estate, mortgage | Real estate – mortgage – home equity loans / lines of credit
Financing Receivable, Past Due [Line Items]
Loans, gross	310,230	337,699
Loans, Excluding Purchased Credit Impaired Loans | Consumer loans
Financing Receivable, Past Due [Line Items]
Loans, gross	$ 50,141	$ 56,083