FAIR VALUE MEASURES - Summary of Significant Unobservable Inputs Used in Fair Value Measurement of Level 3 Assets and Liabilities (Details) $ in Thousands	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt securities available-for-sale, at fair value, net of allowance for credit losses of $— and $112	$ 592,621	$ 982,879
Fair Value, Measurements, Recurring \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt securities available-for-sale, at fair value, net of allowance for credit losses of $— and $112	1,380	1,170
Fair Value, Measurements, Nonrecurring \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral-dependent loans	44,181	98,426
Other real estate owned		4,964
Mortgage servicing rights	$ 206,944	$ 130,630
Discounted par values \| Discount rate \| Fair Value, Measurements, Recurring \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale, measurement input	0.08	0.188
Discounted par values \| Discount rate \| Fair Value, Measurements, Recurring \| Weighted Average \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale, measurement input	0.08	0.188
Discounted par values \| Probability of default \| Fair Value, Measurements, Recurring \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale, measurement input		0.40
Discounted par values \| Probability of default \| Fair Value, Measurements, Recurring \| Weighted Average \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale, measurement input		0.40
Third-party appraisals and discounted cash flows \| Collateral discounts and discount rates \| Fair Value, Measurements, Nonrecurring \| Minimum \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired loans, measurement input	0	0.20
Third-party appraisals and discounted cash flows \| Collateral discounts and discount rates \| Fair Value, Measurements, Nonrecurring \| Maximum \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired loans, measurement input	0.50	0.90
Third-party appraisals and discounted cash flows \| Collateral discounts and discount rates \| Fair Value, Measurements, Nonrecurring \| Weighted Average \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired loans, measurement input	0.39	0.44
Third party appraisals and sales contracts \| Collateral discounts and estimated costs to sell \| Fair Value, Measurements, Nonrecurring \| Minimum \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other real estate owned, measurement input		0.15
Third party appraisals and sales contracts \| Collateral discounts and estimated costs to sell \| Fair Value, Measurements, Nonrecurring \| Maximum \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other real estate owned, measurement input		0.59
Third party appraisals and sales contracts \| Collateral discounts and estimated costs to sell \| Fair Value, Measurements, Nonrecurring \| Weighted Average \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other real estate owned, measurement input		0.28
Discounted cash flows \| Discount rate \| Fair Value, Measurements, Nonrecurring \| Minimum \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage servicing rights measurement input	0.09	0.09
Discounted cash flows \| Discount rate \| Fair Value, Measurements, Nonrecurring \| Maximum \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage servicing rights measurement input	0.10	0.12
Discounted cash flows \| Discount rate \| Fair Value, Measurements, Nonrecurring \| Weighted Average \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage servicing rights measurement input	0.09	0.10
Discounted cash flows \| Prepayment speed \| Fair Value, Measurements, Nonrecurring \| Minimum \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage servicing rights measurement input	0.10	0.14
Discounted cash flows \| Prepayment speed \| Fair Value, Measurements, Nonrecurring \| Maximum \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage servicing rights measurement input	0.40	0.37
Discounted cash flows \| Prepayment speed \| Fair Value, Measurements, Nonrecurring \| Weighted Average \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage servicing rights measurement input	0.13	0.19

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- Definition

Mortgage Servicing Rights

+ References

No definition available.

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- Definition

Mortgage Servicing Rights Measurement Input

+ References

No definition available.

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- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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- Definition

Value of input used to measure investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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- Definition

Value of input used to measure real estate owned by financial institution by financial institution which is not directly related to its business.

+ References

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- Definition

Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

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