FAIR VALUE MEASURES - Summary of Fair Value Measurements of Assets Measured at Fair Value on Non-Recurring Basis (Details) - Fair Value, Measurements, Nonrecurring - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	$ 239,859	$ 61,077
Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	0	0
Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	5,839	0
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	234,020	61,077
Impaired loans carried at fair value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	98,426	43,788
Impaired loans carried at fair value | Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	0	0
Impaired loans carried at fair value | Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	0	0
Impaired loans carried at fair value | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	98,426	43,788
Other real estate owned
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	4,964	17,289
Other real estate owned | Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	0	0
Other real estate owned | Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	0	0
Other real estate owned | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	4,964	$ 17,289
Mortgage servicing rights
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	130,630
Mortgage servicing rights | Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	0
Mortgage servicing rights | Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	0
Mortgage servicing rights | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	130,630
SBA servicing rights
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	5,839
SBA servicing rights | Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	0
SBA servicing rights | Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	5,839
SBA servicing rights | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	$ 0