Allowance for Credit Losses - Changes in the Allowance for Credit Losses (Details) - USD ($) $ in Thousands	12 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 47,058	$ 58,165	$ 37,327
Charge-offs	(896)	(4,737)	(1,612)
Recoveries	86	1,148	30
Initial allowance on PCD loans			3,901
Provision for (reversal of) credit losses	2,486	(7,518)	(1,121)
Ending balance	48,734	47,058	58,165
Impact of adopting Topic 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance			19,640
Commercial loans \| Multi-family mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	25,321	28,450	20,916
Charge-offs	(493)	(1,896)	0
Recoveries	0	0	0
Initial allowance on PCD loans			250
Provision for (reversal of) credit losses	1,534	(1,233)	(1,124)
Ending balance	26,362	25,321	28,450
Commercial loans \| Multi-family mortgage \| Impact of adopting Topic 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance			8,408
Commercial loans \| Nonresidential mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	10,590	16,243	8,763
Charge-offs	(39)	(2,646)	(80)
Recoveries	0	812	0
Initial allowance on PCD loans			1,720
Provision for (reversal of) credit losses	(1,598)	(3,819)	3,450
Ending balance	8,953	10,590	16,243
Commercial loans \| Nonresidential mortgage \| Impact of adopting Topic 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance			2,390
Commercial loans \| Commercial business
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1,792	2,086	1,926
Charge-offs	(364)	(193)	(1,446)
Recoveries	29	160	17
Initial allowance on PCD loans			1,007
Provision for (reversal of) credit losses	(17)	(261)	1,003
Ending balance	1,440	1,792	2,086
Commercial loans \| Commercial business \| Impact of adopting Topic 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance			(421)
Commercial loans \| Construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1,486	1,170	236
Charge-offs	0	0	0
Recoveries	0	0	0
Initial allowance on PCD loans			99
Provision for (reversal of) credit losses	(150)	316	755
Ending balance	1,336	1,486	1,170
Commercial loans \| Construction \| Impact of adopting Topic 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance			80
Residential mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	7,540	9,747	4,860
Charge-offs	0	0	(13)
Recoveries	2	147	4
Initial allowance on PCD loans			720
Provision for (reversal of) credit losses	2,695	(2,354)	(4,930)
Ending balance	10,237	7,540	9,747
Residential mortgage \| Impact of adopting Topic 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance			9,106
Consumer loans \| Home equity loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	245	433	568
Charge-offs	0	0	(32)
Recoveries	0	27	0
Initial allowance on PCD loans			105
Provision for (reversal of) credit losses	93	(215)	(300)
Ending balance	338	245	433
Consumer loans \| Home equity loans \| Impact of adopting Topic 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance			92
Consumer loans \| Other consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	84	36	58
Charge-offs	0	(2)	(41)
Recoveries	55	2	9
Initial allowance on PCD loans			0
Provision for (reversal of) credit losses	(71)	48	25
Ending balance	68	84	36
Consumer loans \| Other consumer \| Impact of adopting Topic 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance			$ (15)
Commercial business \| Multi-family mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	25,321
Ending balance	26,362	25,321
Commercial business \| Nonresidential mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	10,590
Ending balance	8,953	10,590
Commercial business \| Commercial business
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1,792
Ending balance	1,440	1,792
Commercial business \| Construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1,486
Ending balance	$ 1,336	$ 1,486

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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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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

+ 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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- Definition

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

+ 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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- Definition

Amount, excluding accrued interest, of credit loss expense (reversal of expense) on financing receivable from change in methodology. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-11

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- Definition

Amount, excluding accrued interest, of credit loss expense (reversal of expense) on financing receivable. Excludes net investment in lease.

+ 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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