LOANS AND ALLOWANCE FOR CREDIT LOSSES - Allowance for Credit Losses Additional Information (Details) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Sep. 30, 2019 USD ($) Loan	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Jan. 01, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded loan commitments	$ 90,927			$ 90,927		$ 57,649	$ 57,649
Provision for credit losses	1,141	$ 11,826	$ 38,607	28,728	$ 38,805
Collateral lending relationship threshold			$ 5,000
Unfunded Loan Commitment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded loan commitments	3,200			3,200			4,100
Number of loans | Loan			53
Commitments represented			$ 536,000
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded loan commitments	94,133	$ 94,565	67,289	94,133	67,289		61,713	$ 63,818	$ 66,814
Net charge-off	1,573		35,136	2,691	38,330
Provision for credit losses	1,141		38,607	28,728	$ 38,805
Commercial | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded loan commitments						5,941
Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded loan commitments						$ 22,353
Provision for credit losses			3,000
Loans receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest receivable on loans receivable	$ 25,800			$ 25,800			$ 18,900
Loans receivable | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net charge-off			$ 35,100