LOANS RECEIVABLE, NET - Schedule of Activity in Allowance by Portfolio (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Allowance for credit losses:
Beginning balance	$ 65,691	$ 45,031	$ 45,031
Provision for (recovery of) credit losses	890	3,612
Charge-offs	(2,462)	(3,010)
Recoveries	281	461
Ending balance	64,400	67,323	65,691
Adoption of ASU No. 2016-13 \| Accounting Standards Update 2016-13
Allowance for credit losses:
Beginning balance		21,229	21,229
Beginning balance - ACL
Allowance for credit losses:
Beginning balance	65,691	66,260	66,260
Ending balance			65,691
Commercial portfolio \| Commercial and industrial
Allowance for credit losses:
Beginning balance		12,916	12,916
Provision for (recovery of) credit losses	(1,938)	(263)
Charge-offs	(400)		(1,726)
Recoveries	4	4
Ending balance	15,997	16,473
Commercial portfolio \| Commercial and industrial \| Adoption of ASU No. 2016-13 \| Accounting Standards Update 2016-13
Allowance for credit losses:
Beginning balance		3,816	3,816
Commercial portfolio \| Commercial and industrial \| Beginning balance - ACL
Allowance for credit losses:
Beginning balance	18,331	16,732	16,732
Ending balance			18,331
Commercial portfolio \| Multifamily
Allowance for credit losses:
Beginning balance		7,104	7,104
Provision for (recovery of) credit losses	2,315	2,236
Charge-offs	0	(1,127)	(2,367)
Recoveries	0	0
Ending balance	4,448	7,030
Commercial portfolio \| Multifamily \| Adoption of ASU No. 2016-13 \| Accounting Standards Update 2016-13
Allowance for credit losses:
Beginning balance		(1,183)	(1,183)
Commercial portfolio \| Multifamily \| Beginning balance - ACL
Allowance for credit losses:
Beginning balance	2,133	5,921	5,921
Ending balance			2,133
Commercial portfolio \| Commercial real estate
Allowance for credit losses:
Beginning balance		3,627	3,627
Provision for (recovery of) credit losses	129	149
Charge-offs	0	0	0
Recoveries	0	0
Ending balance	1,405	2,455
Commercial portfolio \| Commercial real estate \| Adoption of ASU No. 2016-13 \| Accounting Standards Update 2016-13
Allowance for credit losses:
Beginning balance		(1,321)	(1,321)
Commercial portfolio \| Commercial real estate \| Beginning balance - ACL
Allowance for credit losses:
Beginning balance	1,276	2,306	2,306
Ending balance			1,276
Commercial portfolio \| Construction and land development
Allowance for credit losses:
Beginning balance		825	825
Provision for (recovery of) credit losses	829	(5)
Charge-offs	0	0	(4,664)
Recoveries	0	0
Ending balance	853	354
Commercial portfolio \| Construction and land development \| Adoption of ASU No. 2016-13 \| Accounting Standards Update 2016-13
Allowance for credit losses:
Beginning balance		(466)	(466)
Commercial portfolio \| Construction and land development \| Beginning balance - ACL
Allowance for credit losses:
Beginning balance	24	359	359
Ending balance			24
Commercial portfolio \| Residential real estate lending
Allowance for credit losses:
Provision for (recovery of) credit losses	(853)
Charge-offs	(160)
Recoveries	147
Ending balance	12,407
Commercial portfolio \| Residential real estate lending \| Beginning balance - ACL
Allowance for credit losses:
Beginning balance	13,273
Ending balance			13,273
Retail portfolio \| Residential real estate lending
Allowance for credit losses:
Beginning balance		11,338	11,338
Provision for (recovery of) credit losses		263
Charge-offs	(160)	(58)	(65)
Recoveries		238
Ending balance		14,849
Retail portfolio \| Residential real estate lending \| Adoption of ASU No. 2016-13 \| Accounting Standards Update 2016-13
Allowance for credit losses:
Beginning balance		3,068	3,068
Retail portfolio \| Residential real estate lending \| Beginning balance - ACL
Allowance for credit losses:
Beginning balance		14,406	14,406
Retail portfolio \| Consumer solar
Allowance for credit losses:
Beginning balance		6,867	6,867
Provision for (recovery of) credit losses	482	1,325
Charge-offs	(1,806)	(1,807)	(6,966)
Recoveries	121	211
Ending balance	26,775	22,762
Retail portfolio \| Consumer solar \| Adoption of ASU No. 2016-13 \| Accounting Standards Update 2016-13
Allowance for credit losses:
Beginning balance		16,166	16,166
Retail portfolio \| Consumer solar \| Beginning balance - ACL
Allowance for credit losses:
Beginning balance	27,978	23,033	23,033
Ending balance			27,978
Retail portfolio \| Consumer and Other
Allowance for credit losses:
Beginning balance		2,354	2,354
Provision for (recovery of) credit losses	(74)	(93)
Charge-offs	(96)	(18)	(270)
Recoveries	9	8
Ending balance	2,515	3,400
Retail portfolio \| Consumer and Other \| Adoption of ASU No. 2016-13 \| Accounting Standards Update 2016-13
Allowance for credit losses:
Beginning balance		1,149	1,149
Retail portfolio \| Consumer and Other \| Beginning balance - ACL
Allowance for credit losses:
Beginning balance	$ 2,676	$ 3,503	3,503
Ending balance			$ 2,676

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479344/326-20-45-1

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-13

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-6

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-13

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-13

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