SUBORDINATED DEFERRABLE INTEREST DEBENTURES - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2006	Dec. 31, 2005
Securities Financing Transaction [Line Items]
Trust preferred securities interest rate	4.45%
Preferred stock, value, issued	$ 0	$ 0
First National Banc Statutory Trust I
Securities Financing Transaction [Line Items]
Preferred stock value authorized							$ 5,000,000
Preferred stock spread variable dividend rate							2.80%
Preferred stock maturity period	30 years
Preferred stock, value, outstanding	$ 5,000,000
Long-term debt, gross	5,155,000
Common stock held in trust	$ 155,000
Prosperity Banking Capital Trust I
Securities Financing Transaction [Line Items]
Preferred stock value authorized					$ 5,000,000
Preferred stock spread variable dividend rate					2.57%
Preferred stock maturity period	30 years
Trust preferred securities interest rate	4.26%
Preferred stock, value, outstanding	$ 5,000,000
Long-term debt, gross	5,155,000
Common stock held in trust	155,000
Subordinated debt obligations, net carrying value	$ 3,465,000
Prosperity Banking Capital Trust II
Securities Financing Transaction [Line Items]
Preferred stock value authorized					$ 4,500,000
Preferred stock spread variable dividend rate					3.15%
Preferred stock maturity period	30 years
Trust preferred securities interest rate	4.82%
Preferred stock, value, outstanding	$ 4,500,000
Long-term debt, gross	4,640,000
Common stock held in trust	140,000
Subordinated debt obligations, net carrying value	$ 3,434,000
Prosperity Bank Statutory Trust III
Securities Financing Transaction [Line Items]
Preferred stock value authorized					$ 10,000,000
Preferred stock spread variable dividend rate					1.60%
Preferred stock maturity period	30 years
Trust preferred securities interest rate	3.19%
Preferred stock, value, outstanding	$ 10,000,000
Long-term debt, gross	10,310,000
Common stock held in trust	310,000
Subordinated debt obligations, net carrying value	$ 5,736,000
Prosperity Bank Statutory Trust IV
Securities Financing Transaction [Line Items]
Preferred stock value authorized					$ 10,000,000
Preferred stock spread variable dividend rate					1.54%
Preferred stock maturity period	30 years
Trust preferred securities interest rate	3.13%
Preferred stock, value, outstanding	$ 5,000,000
Long-term debt, gross	5,155,000
Common stock held in trust	310,000
Subordinated debt obligations, net carrying value	$ 3,158,000
Coastal Bankshares Statutory Trust One
Securities Financing Transaction [Line Items]
Preferred stock value authorized				$ 5,000,000
Preferred stock spread variable dividend rate				3.15%
Preferred stock maturity period	30 years
Trust preferred securities interest rate	4.51%
Preferred stock, value, outstanding	$ 5,000,000
Long-term debt, gross	5,155,000
Common stock held in trust	155,000
Subordinated debt obligations, net carrying value	$ 3,936,000
Coastal Bankshares Statutory Trust Two
Securities Financing Transaction [Line Items]
Preferred stock value authorized				$ 10,000,000
Preferred stock spread variable dividend rate				1.60%
Preferred stock maturity period	30 years
Trust preferred securities interest rate	3.19%
Preferred stock, value, outstanding	$ 10,000,000
Long-term debt, gross	10,310,000
Common stock held in trust	310,000
Subordinated debt obligations, net carrying value	$ 6,191,000
Merchants & Southern Statutory Trust I
Securities Financing Transaction [Line Items]
Preferred stock value authorized			$ 3,000,000
Preferred stock spread variable dividend rate			1.90%
Preferred stock maturity period	30 years
Trust preferred securities interest rate	3.50%
Preferred stock, value, outstanding	$ 3,000,000
Long-term debt, gross	3,093,000
Common stock held in trust	93,000
Subordinated debt obligations, net carrying value	$ 2,004,000
Merchants & Southern Statutory Trust II
Securities Financing Transaction [Line Items]
Preferred stock value authorized			$ 3,000,000
Preferred stock spread variable dividend rate			1.50%
Preferred stock maturity period	30 years
Trust preferred securities interest rate	3.09%
Preferred stock, value, outstanding	$ 3,000,000
Long-term debt, gross	3,093,000
Common stock held in trust	93,000
Subordinated debt obligations, net carrying value	$ 1,842,000
Atlantic BancGroup, Inc. Statutory Trust I
Securities Financing Transaction [Line Items]
Preferred stock value authorized		$ 3,000,000
Preferred stock spread variable dividend rate		1.50%
Preferred stock maturity period	30 years
Trust preferred securities interest rate	3.09%
Preferred stock, value, outstanding	$ 3,000,000
Long-term debt, gross	3,093,000
Common stock held in trust	93,000
Subordinated debt obligations, net carrying value	$ 1,787,000
Jacksonville Statutory Trust I
Securities Financing Transaction [Line Items]
Preferred stock value authorized		$ 4,000,000
Preferred stock spread variable dividend rate		2.63%
Preferred stock maturity period	30 years
Trust preferred securities interest rate	4.23%
Preferred stock, value, outstanding	$ 4,000,000
Long-term debt, gross	4,124,000
Common stock held in trust	124,000
Subordinated debt obligations, net carrying value	$ 3,130,000
Jacksonville Statutory Trust II
Securities Financing Transaction [Line Items]
Preferred stock value authorized		$ 3,000,000
Preferred stock spread variable dividend rate		1.73%
Preferred stock maturity period	30 years
Trust preferred securities interest rate	3.32%
Preferred stock, value, outstanding	$ 3,000,000
Long-term debt, gross	3,093,000
Common stock held in trust	93,000
Subordinated debt obligations, net carrying value	$ 1,982,000
Jacksonville Bancorp, Inc. Statutory Trust III
Securities Financing Transaction [Line Items]
Preferred stock value authorized		$ 7,550,000
Preferred stock spread variable dividend rate		3.75%
Preferred stock maturity period	30 years
Trust preferred securities interest rate	5.34%
Preferred stock, value, outstanding	$ 7,550,000
Long-term debt, gross	7,784,000
Common stock held in trust	234,000
Subordinated debt obligations, net carrying value	6,616,000
Ameris Statutory Trust I
Securities Financing Transaction [Line Items]
Preferred stock spread variable dividend rate						1.63%
Long-term debt, gross	37,114,000
Common stock held in trust	$ 1,114,000
Preferred stock and debt rate percentage	3.22%
Preferred stock, value, issued						$ 36,000,000