FAIR VALUE MEASUREMENT - Schedule of Fair Value Hierarchy Measurement (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Assets:
Investment securities AFS	$ 1,060,184	$ 1,002,522
Single family mortgage servicing rights	72,378
Derivatives	2,771	9,280
Liabilities:
Derivative liabilities	6,681	1,263
Residential mortgage-backed securities
Assets:
Investment securities AFS	29,187	32,963
Commercial mortgage-backed securities
Assets:
Investment securities AFS	66,392	62,792
Municipal bonds
Assets:
Investment securities AFS	515,139	539,923
Corporate debt securities
Assets:
Investment securities AFS	26,373	19,616
U.S. Treasury securities
Assets:
Investment securities AFS	21,722	23,175
Recurring
Assets:
Single family LHFS	48,994	128,041
Single family LHFI	6,981	7,287
Single family mortgage servicing rights	72,378	61,584
Total assets	1,219,717	1,207,359
Liabilities:
Total liabilities	9,753	5,184
Recurring \| Residential mortgage-backed securities
Assets:
Investment securities AFS	29,187	32,963
Recurring \| Commercial mortgage-backed securities
Assets:
Investment securities AFS	66,392	62,792
Recurring \| Collateralized mortgage obligations residential
Assets:
Investment securities AFS	266,492	187,394
Recurring \| Collateralized mortgage obligations commercial
Assets:
Investment securities AFS	134,879	136,659
Recurring \| Municipal bonds
Assets:
Investment securities AFS	515,139	539,923
Recurring \| Corporate debt securities
Assets:
Investment securities AFS	26,373	19,616
Recurring \| U.S. Treasury securities
Assets:
Trading securities - U.S. Treasury securities	19,313
Investment securities AFS	21,722	23,175
Recurring \| Futures
Assets:
Derivatives	97	334
Recurring \| Forward sale commitments
Assets:
Derivatives	5,079	723
Liabilities:
Derivative liabilities	3,528	640
Recurring \| Options
Assets:
Derivatives	389
Recurring \| Interest rate lock commitments
Assets:
Derivatives	683	2,487
Liabilities:
Derivative liabilities	605	3
Recurring \| Interest rate swaps
Assets:
Derivatives	5,619	4,381
Liabilities:
Derivative liabilities	5,620	4,541
Level 1 \| Recurring
Assets:
Single family LHFS	0	0
Single family LHFI	0	0
Single family mortgage servicing rights	0	0
Total assets	19,799	334
Liabilities:
Total liabilities	0	0
Level 1 \| Recurring \| Residential mortgage-backed securities
Assets:
Investment securities AFS	0	0
Level 1 \| Recurring \| Commercial mortgage-backed securities
Assets:
Investment securities AFS	0	0
Level 1 \| Recurring \| Collateralized mortgage obligations residential
Assets:
Investment securities AFS	0	0
Level 1 \| Recurring \| Collateralized mortgage obligations commercial
Assets:
Investment securities AFS	0	0
Level 1 \| Recurring \| Municipal bonds
Assets:
Investment securities AFS	0	0
Level 1 \| Recurring \| Corporate debt securities
Assets:
Investment securities AFS	0	0
Level 1 \| Recurring \| U.S. Treasury securities
Assets:
Trading securities - U.S. Treasury securities	19,313
Investment securities AFS	0	0
Level 1 \| Recurring \| Futures
Assets:
Derivatives	97	334
Level 1 \| Recurring \| Forward sale commitments
Assets:
Derivatives	0	0
Liabilities:
Derivative liabilities	0	0
Level 1 \| Recurring \| Options
Assets:
Derivatives	389
Level 1 \| Recurring \| Interest rate lock commitments
Assets:
Derivatives	0	0
Liabilities:
Derivative liabilities	0	0
Level 1 \| Recurring \| Interest rate swaps
Assets:
Derivatives	0	0
Liabilities:
Derivative liabilities	0	0
Level 2 \| Recurring
Assets:
Single family LHFS	48,994	128,041
Single family LHFI	0	0
Single family mortgage servicing rights	0	0
Total assets	1,117,569	1,133,185
Liabilities:
Total liabilities	9,148	5,181
Level 2 \| Recurring \| Residential mortgage-backed securities
Assets:
Investment securities AFS	26,954	30,556
Level 2 \| Recurring \| Commercial mortgage-backed securities
Assets:
Investment securities AFS	66,392	62,792
Level 2 \| Recurring \| Collateralized mortgage obligations residential
Assets:
Investment securities AFS	266,492	187,394
Level 2 \| Recurring \| Collateralized mortgage obligations commercial
Assets:
Investment securities AFS	134,879	136,659
Level 2 \| Recurring \| Municipal bonds
Assets:
Investment securities AFS	515,139	539,923
Level 2 \| Recurring \| Corporate debt securities
Assets:
Investment securities AFS	26,299	19,541
Level 2 \| Recurring \| U.S. Treasury securities
Assets:
Trading securities - U.S. Treasury securities	0
Investment securities AFS	21,722	23,175
Level 2 \| Recurring \| Futures
Assets:
Derivatives	0	0
Level 2 \| Recurring \| Forward sale commitments
Assets:
Derivatives	5,079	723
Liabilities:
Derivative liabilities	3,528	640
Level 2 \| Recurring \| Options
Assets:
Derivatives	0
Level 2 \| Recurring \| Interest rate lock commitments
Assets:
Derivatives	0	0
Liabilities:
Derivative liabilities	0	0
Level 2 \| Recurring \| Interest rate swaps
Assets:
Derivatives	5,619	4,381
Liabilities:
Derivative liabilities	5,620	4,541
Level 3 \| Recurring
Assets:
Single family LHFS	0	0
Single family LHFI	6,981	7,287
Single family mortgage servicing rights	72,378	61,584
Total assets	82,349	73,840
Liabilities:
Total liabilities	605	3
Level 3 \| Recurring \| Residential mortgage-backed securities
Assets:
Investment securities AFS	2,233	2,407
Level 3 \| Recurring \| Commercial mortgage-backed securities
Assets:
Investment securities AFS	0	0
Level 3 \| Recurring \| Collateralized mortgage obligations residential
Assets:
Investment securities AFS	0	0
Level 3 \| Recurring \| Collateralized mortgage obligations commercial
Assets:
Investment securities AFS	0	0
Level 3 \| Recurring \| Municipal bonds
Assets:
Investment securities AFS	0	0
Level 3 \| Recurring \| Corporate debt securities
Assets:
Investment securities AFS	74	75
Level 3 \| Recurring \| U.S. Treasury securities
Assets:
Trading securities - U.S. Treasury securities	0
Investment securities AFS	0	0
Level 3 \| Recurring \| Futures
Assets:
Derivatives	0	0
Level 3 \| Recurring \| Forward sale commitments
Assets:
Derivatives	0	0
Liabilities:
Derivative liabilities	0	0
Level 3 \| Recurring \| Options
Assets:
Derivatives	0
Level 3 \| Recurring \| Interest rate lock commitments
Assets:
Derivatives	683	2,487
Liabilities:
Derivative liabilities	605	3
Level 3 \| Recurring \| Interest rate swaps
Assets:
Derivatives	0	0
Liabilities:
Derivative liabilities	$ 0	$ 0

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount excluding accrued interest, 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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Fair value of financial and nonfinancial obligations.

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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