Loans and Asset Quality Information (Schedule of Analysis of Payment Status of Loans) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	$ 25,066	$ 24,866
Accruing Current	4,495,825	4,402,978
Loans, gross	4,550,996	4,451,525	$ 4,302,163
Unamortized net deferred loan costs	1,712	1,941	1,624
Total loans	4,552,708	4,453,466	4,303,787
Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	21,685	17,236
Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	7,674	5,683
Accruing 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	746	762
PCI Loans
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	0	0
Accruing Current	8,453	11,646
Loans, gross	9,839	12,664
PCI Loans | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	625	218
PCI Loans | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	15	38
PCI Loans | Accruing 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	746	762
Commercial, financial, and agricultural
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	3,703	5,518
Accruing Current	514,992	497,788
Loans, gross	521,470	504,271	468,388
Commercial, financial, and agricultural | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	2,387	752
Commercial, financial, and agricultural | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	201	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 – mortgage – commercial and other
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	9,837	8,820
Accruing Current	1,944,844	1,897,573
Loans, gross	1,970,716	1,917,280	1,794,794
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	4,850	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	7,164	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, commercial | Real estate – construction, land development & other land loans
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	958	1,067
Accruing Current	587,989	529,444
Loans, gross	590,485	530,866	553,760
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	1,333	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	42	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, mortgage | Real estate – mortgage – home equity loans / lines of credit
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	1,874	1,797
Accruing Current	327,516	334,832
Loans, gross	331,170	337,922	354,669
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	1,532	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	155	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
Real estate, mortgage | Real estate – mortgage – residential (1-4 family) first mortgages
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	8,581	7,552
Accruing Current	1,058,281	1,076,205
Loans, gross	1,083,022	1,105,014	1,061,049
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	10,829	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	30	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
Consumer loans
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	113	112
Accruing Current	53,750	55,490
Loans, gross	54,133	56,172	$ 69,503
Consumer loans | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	129	344
Consumer loans | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, past due	67	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	521,283	504,058
Loans, Excluding Purchased Credit Impaired Loans | Real estate, commercial | Real estate – mortgage – commercial and other
Financing Receivable, Past Due [Line Items]
Loans, gross	1,966,695	1,910,650
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	590,322	530,700
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	331,077	337,699
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	1,077,721	1,099,671
Loans, Excluding Purchased Credit Impaired Loans | Consumer loans
Financing Receivable, Past Due [Line Items]
Loans, gross	$ 54,059	$ 56,083