Loans, Allowance for Credit Losses, and Asset Quality Information (Summary of Major Categories of Total Loans Outstanding) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Loans and Leases Receivable Disclosure [Line Items]
Loans, gross	$ 4,630,597	$ 4,735,013	$ 4,550,996
Unamortized net deferred loan costs (fees)	(6,543)	(3,698)	1,712
Loans	$ 4,624,054	$ 4,731,315	4,552,708
Percentage	100.00%	100.00%
SBA Loans
Loans and Leases Receivable Disclosure [Line Items]
Loans	$ 168,924	$ 169,662
SBA Loans, Guaranteed Portion
Loans and Leases Receivable Disclosure [Line Items]
Loans	35,007	33,959
SBA Loans, Unguaranteed Portion
Loans and Leases Receivable Disclosure [Line Items]
Loans	133,917	135,703
SBA Loans, Sold Portion
Loans and Leases Receivable Disclosure [Line Items]
Loans	412,472	395,398
Commercial, financial, and agricultural
Loans and Leases Receivable Disclosure [Line Items]
Loans, gross	$ 768,318	$ 782,549	521,470
Percentage	17.00%	17.00%
Real estate, commercial \| Real estate – construction, land development & other land loans
Loans and Leases Receivable Disclosure [Line Items]
Loans, gross	$ 548,508	$ 570,672	590,485
Percentage	12.00%	12.00%
Real estate, commercial \| Real estate – mortgage – commercial and other
Loans and Leases Receivable Disclosure [Line Items]
Loans, gross	$ 2,049,507	$ 2,049,203	1,970,716
Percentage	44.00%	43.00%
Real estate, mortgage \| Real estate – mortgage – residential (1-4 family) first mortgages
Loans and Leases Receivable Disclosure [Line Items]
Loans, gross	$ 916,169	$ 972,378	1,083,022
Percentage	20.00%	21.00%
Real estate, mortgage \| Real estate – mortgage – home equity loans / lines of credit
Loans and Leases Receivable Disclosure [Line Items]
Loans, gross	$ 294,611	$ 306,256	331,170
Percentage	6.00%	6.00%
Consumer loans
Loans and Leases Receivable Disclosure [Line Items]
Loans, gross	$ 53,484	$ 53,955	$ 54,133
Percentage	1.00%	1.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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