Borrowed Funds - Schedule of Other Borrowings (Detail) $ in Thousands	12 Months Ended
Dec. 31, 2019 USD ($)
Capital lease
Debt Instrument [Line Items]
Stated Value	$ 109,453
Carrying Value	96,801
Maturing September 30, 2026 \| Subordinated debt
Debt Instrument [Line Items]
Stated Value	35,000
Carrying Value	$ 34,542
Debt instrument, interest rate, stated percentage	5.125%
Maturing September 30, 2026 \| Subordinated debt \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Floating rate percentage	392.00%
Maturing August 1, 2036 \| Trust preferred
Debt Instrument [Line Items]
Stated Value	$ 5,000
Carrying Value	$ 5,000
Maturing August 1, 2036 \| Trust preferred \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Floating rate percentage	165.00%
Maturing March 15, 2036 \| Trust preferred
Debt Instrument [Line Items]
Stated Value	$ 30,000
Carrying Value	$ 22,645
Maturing March 15, 2036 \| Trust preferred \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Floating rate percentage	135.00%
Maturing November 1, 2036 \| Trust preferred
Debt Instrument [Line Items]
Stated Value	$ 7,500
Carrying Value	$ 7,500
Maturing November 1, 2036 \| Trust preferred \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Floating rate percentage	166.00%
Maturing April 19, 2037 \| Trust preferred
Debt Instrument [Line Items]
Stated Value	$ 10,000
Carrying Value	$ 7,652
Maturing April 19, 2037 \| Trust preferred \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Floating rate percentage	153.00%
Maturing September 1, 2037 \| Trust preferred
Debt Instrument [Line Items]
Stated Value	$ 10,000
Carrying Value	$ 10,000
Maturing September 1, 2037 \| Trust preferred \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Floating rate percentage	175.00%
Maturing October 1, 2037 \| Trust preferred
Debt Instrument [Line Items]
Stated Value	$ 10,000
Carrying Value	$ 7,509
Maturing October 1, 2037 \| Trust preferred \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Floating rate percentage	139.00%
Maturing June 30, 2029 \| Capital lease
Debt Instrument [Line Items]
Stated Value	$ 1,953
Carrying Value	$ 1,953
Debt instrument, interest rate, stated percentage	5.625%

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

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

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_CapitalLeaseObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ocfc_MaturingSeptember302026Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SubordinatedDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ocfc_MaturingAugust12036Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=ocfc_TrustPreferredSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ocfc_MaturingMarch152036Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ocfc_MaturingNovember12036Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ocfc_MaturingApril192037Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ocfc_MaturingSeptember12037Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ocfc_MaturingOctober12037Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ocfc_MaturingJune302029Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: