Leases - Narrative (Details) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021 USD ($)	Sep. 30, 2021 USD ($) lease branch
Leases [Abstract]
Number of finance leases \| lease		1
Number of branch locations \| branch		20
Finance lease income, premises, equipment and right-of-use asset \| $	$ 3.8	$ 3.8

Income From Premises, Equipment and Right-of-Use Asset

No definition available.

Name:	ocfc_IncomeFromPremisesEquipmentAndRightOfUseAsset
Namespace Prefix:	ocfc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration