FAIR VALUE MEASUREMENTS - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Fair Value Measurements Disclosure [Line Items]
Transfer of equity security to non-marketable equity securities, included in other assets	$ 0	$ 0
Collateral dependent loans, allowance for credit loss	8,200,000
Provision for fair value measurements included in allowance for loan losses	2,100,000
Carrying amount of OREO	1,100,000
Valuation allowance of OREO	300,000
Loss from OREO included in earnings	300,000
Fair Value, Nonrecurring [Member]
Fair Value Measurements Disclosure [Line Items]
Collateral dependent loans carrying value	9,500,000
Mortgage Servicing Rights [Member] | Fair Value, Nonrecurring [Member]
Fair Value Measurements Disclosure [Line Items]
Servicing asset	15,500,000
Valuation allowance for impairment of recognized servicing assets, additions (deductions) for expenses (recoveries)	3,500,000
Mortgage Servicing Rights [Member] | Fair Value, Nonrecurring [Member] | Provision Expense [Member]
Fair Value Measurements Disclosure [Line Items]
Valuation allowance for impairment of recognized servicing assets, provision recovery	3,800,000
SBA-Guaranteed Loan Servicing [Member] | Fair Value, Nonrecurring [Member]
Fair Value Measurements Disclosure [Line Items]
Servicing asset	5,300,000
Valuation allowance for impairment of recognized servicing assets, additions (deductions) for expenses (recoveries)	900,000
Valuation allowance for impairment of recognized servicing assets, provision recovery	$ 200,000