FAIR VALUE MEASURES - Fair Value Measurements of Assets Measured at Fair Value on Non-Recurring Basis (Details) - Fair Value, Measurements, Nonrecurring - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	$ 147,205	$ 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	91,316	0
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	55,889	61,077
Collateral-dependent loans
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	53,368	43,788
Collateral-dependent loans | Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	0	0
Collateral-dependent loans | Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	0	0
Collateral-dependent loans | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	53,368	43,788
Other real estate owned
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	2,521	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	2,521	$ 17,289
Mortgage servicing rights
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	85,922
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	85,922
Mortgage servicing rights | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	0
SBA servicing rights
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	5,394
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	5,394
SBA servicing rights | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets at fair value	$ 0