Cash and Cash Equivalents Concentrations - Schedule of Amounts Due from Correspondent Institutions having Concentration of Credit Risk (Details) - Credit Concentration Risk - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Concentration Risk [Line Items]
Cash due from Correspondent institutions	$ 34,336	$ 106,828
First Tennessee Bank, N.A.
Concentration Risk [Line Items]
Cash due from Correspondent institutions	2,477	26,381
Federal Reserve Bank of Atlanta
Concentration Risk [Line Items]
Cash due from Correspondent institutions	22,103	61,623
JP Morgan Chase Bank, N.A.
Concentration Risk [Line Items]
Cash due from Correspondent institutions	3,138	2,272
Fifth Third Bank
Concentration Risk [Line Items]
Cash due from Correspondent institutions	1,558	1,598
BBVA Compass
Concentration Risk [Line Items]
Cash due from Correspondent institutions	1,065	987
Zions Bank, N.A.
Concentration Risk [Line Items]
Cash due from Correspondent institutions	500	501
Servis First Bank
Concentration Risk [Line Items]
Cash due from Correspondent institutions	350	350
Sun Trust Bank
Concentration Risk [Line Items]
Cash due from Correspondent institutions	230	232
PNC Bank, N.A.
Concentration Risk [Line Items]
Cash due from Correspondent institutions	211	213
First National Bankers Bank
Concentration Risk [Line Items]
Cash due from Correspondent institutions	200	200
US Bank, N.A.
Concentration Risk [Line Items]
Cash due from Correspondent institutions	98
Wells Fargo Bank, N.A.
Concentration Risk [Line Items]
Cash due from Correspondent institutions	88
Alostar Bank of Commerce
Concentration Risk [Line Items]
Cash due from Correspondent institutions	538
Synovus Bank
Concentration Risk [Line Items]
Cash due from Correspondent institutions	291	1,062
Federal Home Loan Bank of Cincinnati
Concentration Risk [Line Items]
Cash due from Correspondent institutions	$ 1,489	$ 11,409