Loans Receivable - Summary of Average Recorded Investment and Interest Income Recognized on Loans Individually Evaluated for Impairment, by Portfolio Segment (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Financing Receivable Impaired [Line Items]
Impaired loans average recorded investment	$ 8,821	$ 4,407	$ 7,763	$ 4,528
Impaired loans interest income recognized	35	58	268	183
Residential Mortgages [Member]
Financing Receivable Impaired [Line Items]
Impaired loans with no related allowance recorded, average recorded investment	1,472	1,822	1,750	1,905
Impaired loans with no related allowance recorded, interest income recognized	16	7	46	27
Impaired loans with an allowance recorded, average recorded investment	418	427	421	429
Impaired loans with an allowance recorded, interest income recognized	3	4	10	11
Commercial Mortgages [Member]
Financing Receivable Impaired [Line Items]
Impaired loans with no related allowance recorded, average recorded investment	4,790		4,065
Impaired loans with no related allowance recorded, interest income recognized	12		12
Construction [Member]
Financing Receivable Impaired [Line Items]
Impaired loans with no related allowance recorded, average recorded investment	1,113		445
Commercial Loans [Member]
Financing Receivable Impaired [Line Items]
Impaired loans with no related allowance recorded, average recorded investment	653	1,749	704	1,786
Impaired loans with no related allowance recorded, interest income recognized	3	47	197	144
Home Equity Lines Of Credit [Member]
Financing Receivable Impaired [Line Items]
Impaired loans with no related allowance recorded, average recorded investment	339	379	343	384
Impaired loans with no related allowance recorded, interest income recognized			2	1
Impaired loans with an allowance recorded, average recorded investment	36	$ 30	35	$ 24
Impaired loans with an allowance recorded, interest income recognized	$ 1		$ 1

Impaired financing receivable interest income (loss) accrual method.

No definition available.

Name:	pcsb_ImpairedFinancingReceivableInterestIncomeLossAccrualMethod
Namespace Prefix:	pcsb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Impaired financing receivable with no related allowance interest income (expense) accrual method.

+ References

No definition available.

+ Details

Name:	pcsb_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeExpenseAccrualMethod
Namespace Prefix:	pcsb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_FinancingReceivableImpairedLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5258-111524

+ Details

Name:	us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5258-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524

+ Details

Name:	us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of interest income, recognized on accrual basis, on financing receivables, for which there is a related allowance for credit losses and are recognized as impaired.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=pcsb_ResidentialMortgagesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=pcsb_CommercialMortgagesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=pcsb_ConstructionPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=pcsb_HomeEquityPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: