SUBORDINATED DEFERRABLE INTEREST DEBENTURES - Subordinated Deferrable Interest Debentures (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Securities Financing Transaction [Line Items]
Issuance Amount	$ 154,390
Unaccreted Purchase Discount	30,045
Carrying Value	$ 124,345
Prosperity Bank Statutory Trust II
Securities Financing Transaction [Line Items]
Trust preferred securities, variable basis spread	3.15%
Trust preferred securities interest rate	3.40%
Issuance Amount	$ 4,640
Unaccreted Purchase Discount	969
Carrying Value	$ 3,671
Fidelity Southern Statutory Trust I
Securities Financing Transaction [Line Items]
Trust preferred securities, variable basis spread	3.10%
Trust preferred securities interest rate	3.35%
Issuance Amount	$ 15,464
Unaccreted Purchase Discount	1,227
Carrying Value	$ 14,237
Coastal Bankshares Statutory Trust I
Securities Financing Transaction [Line Items]
Trust preferred securities, variable basis spread	3.15%
Trust preferred securities interest rate	3.39%
Issuance Amount	$ 5,155
Unaccreted Purchase Discount	987
Carrying Value	$ 4,168
Jacksonville Statutory Trust I
Securities Financing Transaction [Line Items]
Trust preferred securities, variable basis spread	2.63%
Trust preferred securities interest rate	2.86%
Issuance Amount	$ 4,124
Unaccreted Purchase Discount	812
Carrying Value	$ 3,312
Prosperity Banking Capital Trust I
Securities Financing Transaction [Line Items]
Trust preferred securities, variable basis spread	2.57%
Trust preferred securities interest rate	2.81%
Issuance Amount	$ 5,155
Unaccreted Purchase Discount	1,383
Carrying Value	$ 3,772
Merchants & Southern Statutory Trust I
Securities Financing Transaction [Line Items]
Trust preferred securities, variable basis spread	1.90%
Trust preferred securities interest rate	2.13%
Issuance Amount	$ 3,093
Unaccreted Purchase Discount	899
Carrying Value	$ 2,194
Fidelity Southern Statutory Trust II
Securities Financing Transaction [Line Items]
Trust preferred securities, variable basis spread	1.89%
Trust preferred securities interest rate	2.12%
Issuance Amount	$ 10,310
Unaccreted Purchase Discount	2,047
Carrying Value	$ 8,263
Atlantic BancGroup, Inc. Statutory Trust I
Securities Financing Transaction [Line Items]
Trust preferred securities, variable basis spread	1.50%
Trust preferred securities interest rate	1.72%
Issuance Amount	$ 3,093
Unaccreted Purchase Discount	1,134
Carrying Value	$ 1,959
Coastal Bankshares Statutory Trust II
Securities Financing Transaction [Line Items]
Trust preferred securities, variable basis spread	1.60%
Trust preferred securities interest rate	1.82%
Issuance Amount	$ 10,310
Unaccreted Purchase Discount	3,429
Carrying Value	$ 6,881
Cherokee Statutory Trust I
Securities Financing Transaction [Line Items]
Trust preferred securities, variable basis spread	1.50%
Trust preferred securities interest rate	1.72%
Issuance Amount	$ 3,093
Unaccreted Purchase Discount	686
Carrying Value	$ 2,407
Prosperity Bank Statutory Trust III
Securities Financing Transaction [Line Items]
Trust preferred securities, variable basis spread	1.60%
Trust preferred securities interest rate	1.82%
Issuance Amount	$ 10,310
Unaccreted Purchase Discount	3,815
Carrying Value	$ 6,495
Merchants & Southern Statutory Trust II
Securities Financing Transaction [Line Items]
Trust preferred securities, variable basis spread	1.50%
Trust preferred securities interest rate	1.72%
Issuance Amount	$ 3,093
Unaccreted Purchase Discount	1,046
Carrying Value	$ 2,047
Jacksonville Statutory Trust II
Securities Financing Transaction [Line Items]
Trust preferred securities, variable basis spread	1.73%
Trust preferred securities interest rate	1.95%
Issuance Amount	$ 3,093
Unaccreted Purchase Discount	934
Carrying Value	$ 2,159
Ameris Statutory Trust I
Securities Financing Transaction [Line Items]
Trust preferred securities, variable basis spread	1.63%
Trust preferred securities interest rate	1.85%
Issuance Amount	$ 37,114
Unaccreted Purchase Discount	0
Carrying Value	$ 37,114
Fidelity Southern Statutory Trust III
Securities Financing Transaction [Line Items]
Trust preferred securities, variable basis spread	1.40%
Trust preferred securities interest rate	1.62%
Issuance Amount	$ 20,619
Unaccreted Purchase Discount	5,542
Carrying Value	$ 15,077
Prosperity Bank Statutory Trust IV
Securities Financing Transaction [Line Items]
Trust preferred securities, variable basis spread	1.54%
Trust preferred securities interest rate	1.76%
Issuance Amount	$ 7,940
Unaccreted Purchase Discount	4,139
Carrying Value	$ 3,801
Jacksonville Bancorp, Inc. Statutory Trust III
Securities Financing Transaction [Line Items]
Trust preferred securities, variable basis spread	3.75%
Trust preferred securities interest rate	3.97%
Issuance Amount	$ 7,784
Unaccreted Purchase Discount	996
Carrying Value	$ 6,788