LOANS AND LEASES RECEIVABLE AND ALLOWANCE FOR CREDIT LOSSES ON LOANS AND LEASES - Schedule of Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
Mar. 31, 2025	Mar. 31, 2024	Jun. 30, 2024	Dec. 31, 2024
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 136,775	$ 135,311	$ 135,311	$ 135,311
Charge-offs	(20,763)	(22,827)	(84,465)
Recoveries	3,619	4,859
Provision (benefit) for credit losses on loans and leases	21,445	15,953
Ending balance	141,076	133,296		136,775
Commercial and industrial, including specialized lending
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	29,379	23,503	23,503	23,503
Charge-offs	(4,507)	(5,396)
Recoveries	1,276	1,724
Provision (benefit) for credit losses on loans and leases	4,436	3,172
Ending balance	30,584	23,003		29,379
Multifamily
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	18,511	16,343	16,343	16,343
Charge-offs	(3,834)	(473)
Recoveries	0	0
Provision (benefit) for credit losses on loans and leases	4,113	2,437
Ending balance	18,790	18,307		18,511
Commercial real estate owner occupied
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	10,755	9,882	9,882	9,882
Charge-offs	(19)	(22)
Recoveries	3	0
Provision (benefit) for credit losses on loans and leases	41	341
Ending balance	10,780	10,201		10,755
Commercial real estate non-owner occupied
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	17,405	16,859	16,859	16,859
Charge-offs	0	0
Recoveries	0	0
Provision (benefit) for credit losses on loans and leases	653	1,461
Ending balance	18,058	18,320		17,405
Construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1,250	1,482	1,482	1,482
Charge-offs	0	0
Recoveries	3	0
Provision (benefit) for credit losses on loans and leases	11	384
Ending balance	1,264	1,866		1,250
Residential real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	5,968	6,586	6,586	6,586
Charge-offs	0	(19)
Recoveries	0	1
Provision (benefit) for credit losses on loans and leases	195	139
Ending balance	6,163	6,707		5,968
Manufactured housing
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	3,829	4,239	4,239	4,239
Charge-offs	0	0
Recoveries	0	0
Provision (benefit) for credit losses on loans and leases	(29)	(79)
Ending balance	3,800	4,160		3,829
Installment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	49,678	56,417	$ 56,417	56,417
Charge-offs	(12,403)	(16,917)
Recoveries	2,337	3,134
Provision (benefit) for credit losses on loans and leases	12,025	8,098
Ending balance	$ 51,637	$ 50,732		$ 49,678

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
-Topic 326
-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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