Loans Receivable, Net - Troubled Debt Restructurings (Detail) $ in Thousands	12 Months Ended
Dec. 31, 2018 USD ($) SecurityLoan	Dec. 31, 2017 USD ($) SecurityLoan
Commercial and industrial
Financing Receivable, Modifications [Line Items]
Number of Loans \| SecurityLoan	2	1
Pre-modification Recorded Investment	$ 496	$ 665
Post-modification Recorded Investment	$ 502	$ 665
Commercial real estate – owner occupied
Financing Receivable, Modifications [Line Items]
Number of Loans \| SecurityLoan	1	7
Pre-modification Recorded Investment	$ 49	$ 6,977
Post-modification Recorded Investment	$ 50	$ 6,977
Commercial real estate – investor
Financing Receivable, Modifications [Line Items]
Number of Loans \| SecurityLoan	3	7
Pre-modification Recorded Investment	$ 1,395	$ 10,904
Post-modification Recorded Investment	$ 1,435	$ 11,026
Residential mortgage
Financing Receivable, Modifications [Line Items]
Number of Loans \| SecurityLoan	5	8
Pre-modification Recorded Investment	$ 558	$ 1,637
Post-modification Recorded Investment	$ 598	$ 1,600
Consumer
Financing Receivable, Modifications [Line Items]
Number of Loans \| SecurityLoan	1
Recorded Investment	$ 29
Subsequently Defaulted
Financing Receivable, Modifications [Line Items]
Number of Loans \| SecurityLoan		0
Recorded Investment		$ 0

Financing Receivable Modifications Post Modification Recorded Investment During Period

No definition available.

Name:	ocfc_FinancingReceivableModificationsPostModificationRecordedInvestmentDuringPeriod
Namespace Prefix:	ocfc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Financing Receivable Modifications Pre Modification Recorded Investment During Period

+ References

No definition available.

+ Details

Name:	ocfc_FinancingReceivableModificationsPreModificationRecordedInvestmentDuringPeriod
Namespace Prefix:	ocfc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Trouble Debt Restructuring Modifications Recorded Investment

+ References

No definition available.

+ Details

Name:	ocfc_TroubleDebtRestructuringModificationsRecordedInvestment
Namespace Prefix:	ocfc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_FinancingReceivableModificationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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