Loan Quality and Allowance for Loan Losses - Impairment Status of Loans Receivable (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018	Jun. 30, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-impaired loans	$ 4,689,543		$ 4,689,543		$ 4,544,634
Impaired loans with no allowance for impairment	25,288		25,288		22,279
Recorded investment	685		685		1,002
Allowance for impairment	(318)		(318)		(306)
Balance of impaired loans net of allowance for impairment	367		367		696
Total impaired loans, excluding allowance for impairment:	25,973		25,973		23,281
Loans and Leases Receivable, Gross	4,715,516		4,715,516		4,567,915
Unpaid principal balance of impaired loans	40,027		40,027		37,705
Average balance of impaired loans	26,285	$ 19,541	25,058	$ 20,618
Interest earned on impaired loans	60	43	171	131
Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-impaired loans	1,311,569		1,311,569		1,285,423
Impaired loans with no allowance for impairment	13,133		13,133		11,255
Recorded investment	403		403		775
Allowance for impairment	(36)		(36)		(79)
Balance of impaired loans net of allowance for impairment	367		367		696
Total impaired loans, excluding allowance for impairment:	13,536		13,536		12,030
Loans and Leases Receivable, Gross	1,325,105		1,325,105		1,297,453
Unpaid principal balance of impaired loans	18,617		18,617		16,263
Average balance of impaired loans	13,766	8,048	13,014	9,019
Interest earned on impaired loans	32	33	97	99
Non-Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-impaired loans	1,240,259		1,240,259		1,297,617
Impaired loans with no allowance for impairment	8,956		8,956		5,344
Total impaired loans, excluding allowance for impairment:	8,956		8,956		5,344
Loans and Leases Receivable, Gross	1,249,215		1,249,215		1,302,961
Unpaid principal balance of impaired loans	12,266		12,266		10,033
Average balance of impaired loans	8,750	7,038	8,039	6,823
Interest earned on impaired loans				4
Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-impaired loans	14,377		14,377		23,271
Loans and Leases Receivable, Gross	14,377		14,377		23,271
Unpaid principal balance of impaired loans	106		106		106
Average balance of impaired loans				137
Commercial Business [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-impaired loans	64,601		64,601		81,635
Impaired loans with no allowance for impairment	1,593		1,593		3,963
Recorded investment	282		282		227
Allowance for impairment	(282)		(282)		(227)
Total impaired loans, excluding allowance for impairment:	1,875		1,875		4,190
Loans and Leases Receivable, Gross	66,476		66,476		85,825
Unpaid principal balance of impaired loans	5,350		5,350		7,671
Average balance of impaired loans	2,143	2,762	2,352	2,805
Interest earned on impaired loans	19	1	48	4
Other Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-impaired loans	5,984		5,984		9,060
Loans and Leases Receivable, Gross	5,984		5,984		9,060
Multi-Family Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-impaired loans	1,956,490		1,956,490		1,758,468
Impaired loans with no allowance for impairment	81		81		116
Total impaired loans, excluding allowance for impairment:	81		81		116
Loans and Leases Receivable, Gross	1,956,571		1,956,571		1,758,584
Unpaid principal balance of impaired loans	930		930		930
Average balance of impaired loans	86	130	97	141
Home Equity Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-impaired loans	96,263		96,263		89,160
Impaired loans with no allowance for impairment	1,525		1,525		1,601
Total impaired loans, excluding allowance for impairment:	1,525		1,525		1,601
Loans and Leases Receivable, Gross	97,788		97,788		90,761
Unpaid principal balance of impaired loans	2,758		2,758		$ 2,702
Average balance of impaired loans	1,540	1,563	1,556	1,693
Interest earned on impaired loans	$ 9	$ 9	$ 26	$ 24

Impaired (recovered) financing receivables with related allowance recorded investment.

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- Definition

The balance of financing receivables that were collectively evaluated for impairment.

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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

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Amount of allowance for credit losses related to recorded investment.

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Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

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Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

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Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

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- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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