FAIR VALUE MEASUREMENT - Schedule of Quantitative Information (Details) $ in Thousands	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Key economic assumptions and the sensitivity of the current fair valu for single family MSRs
Investment securities AFS	$ 1,002,522	$ 1,072,093
Fair Value, Recurring
Key economic assumptions and the sensitivity of the current fair valu for single family MSRs
Fair value of loans held for investment	7,287	7,108
Fair Value, Recurring \| Level 3
Key economic assumptions and the sensitivity of the current fair valu for single family MSRs
Investment securities AFS	2,482	2,710
Fair value of loans held for investment	7,287	7,108
Fair Value, Recurring \| Level 3 \| Single Family
Key economic assumptions and the sensitivity of the current fair valu for single family MSRs
Fair value of loans held for investment	$ 7,287	$ 7,108
Implied spread to benchmark interest rate curve \| Fair Value, Recurring \| Level 3 \| Minimum
Key economic assumptions and the sensitivity of the current fair valu for single family MSRs
Investment securities available for sale, measurement input	0.0200	0.0200
Implied spread to benchmark interest rate curve \| Fair Value, Recurring \| Level 3 \| Minimum \| Single Family
Key economic assumptions and the sensitivity of the current fair valu for single family MSRs
Loans held for investment, measurement input	0.0239	0.0396
Implied spread to benchmark interest rate curve \| Fair Value, Recurring \| Level 3 \| Maximum
Key economic assumptions and the sensitivity of the current fair valu for single family MSRs
Investment securities available for sale, measurement input	0.0200	0.0200
Implied spread to benchmark interest rate curve \| Fair Value, Recurring \| Level 3 \| Maximum \| Single Family
Key economic assumptions and the sensitivity of the current fair valu for single family MSRs
Loans held for investment, measurement input	0.0796	0.1064
Implied spread to benchmark interest rate curve \| Fair Value, Recurring \| Level 3 \| Weighted Average
Key economic assumptions and the sensitivity of the current fair valu for single family MSRs
Investment securities available for sale, measurement input	0.0200	0.0200
Implied spread to benchmark interest rate curve \| Fair Value, Recurring \| Level 3 \| Weighted Average \| Single Family
Key economic assumptions and the sensitivity of the current fair valu for single family MSRs
Loans held for investment, measurement input	0.0356	0.0623
Interest rate lock commitments \| Fair Value, Recurring \| Level 3
Key economic assumptions and the sensitivity of the current fair valu for single family MSRs
Interest rate lock and purchase loan commitments, net	$ 2,484	$ 17,392
Interest rate lock commitments \| Fall-out factor \| Fair Value, Recurring \| Level 3 \| Minimum
Key economic assumptions and the sensitivity of the current fair valu for single family MSRs
Interest rate lock and purchase loan commitments, net, measurement input	0.0015	0.0197
Interest rate lock commitments \| Fall-out factor \| Fair Value, Recurring \| Level 3 \| Maximum
Key economic assumptions and the sensitivity of the current fair valu for single family MSRs
Interest rate lock and purchase loan commitments, net, measurement input	0.2193	0.3838
Interest rate lock commitments \| Fall-out factor \| Fair Value, Recurring \| Level 3 \| Weighted Average
Key economic assumptions and the sensitivity of the current fair valu for single family MSRs
Interest rate lock and purchase loan commitments, net, measurement input	0.0844	0.1553
Interest rate lock commitments \| Value of servicing \| Fair Value, Recurring \| Level 3 \| Minimum
Key economic assumptions and the sensitivity of the current fair valu for single family MSRs
Interest rate lock and purchase loan commitments, net, measurement input	0.0035	0.0041
Interest rate lock commitments \| Value of servicing \| Fair Value, Recurring \| Level 3 \| Maximum
Key economic assumptions and the sensitivity of the current fair valu for single family MSRs
Interest rate lock and purchase loan commitments, net, measurement input	0.0146	0.0144
Interest rate lock commitments \| Value of servicing \| Fair Value, Recurring \| Level 3 \| Weighted Average
Key economic assumptions and the sensitivity of the current fair valu for single family MSRs
Interest rate lock and purchase loan commitments, net, measurement input	0.0115	0.0097

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Amount of 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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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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Value of input used to measure derivative asset.

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Fair value of financial instrument classified as derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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