LOANS AND ALLOWANCE FOR CREDIT LOSSES - Narrative (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2021 USD ($) contract	Mar. 31, 2020 USD ($) contract	Dec. 31, 2020 USD ($) contract
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses provision	$ 0	$ 1,400,000
Loan basis points	0.42%		0.55%
Percentage of loan growth excluding PPP loans	1.60%
Loans classified in doubtful or loss risk rating	$ 0		$ 0
Number of loans modified as TDRs | contract	1	0	4
Increase in allowance for loan losses due to TDRs	$ 0		$ 0
Troubled debt restructuring charge-offs	$ 0		0
COVID-19
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses provision			$ 13,200,000