Document and Entity Information
| Document and Entity Information | Sep. 09, 2019 |
| Cover page. | |
| Document Type | 8-K |
| Document Period End Date | Sep. 9, 2019 |
| Entity Registrant Name | OCEANFIRST FINANCIAL CORP. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-11713 |
| Entity Tax Identification Number | 22-3412577 |
| Entity Address, Address Line One | 110 West Front Street |
| Entity Address, City or Town | Red Bank |
| Entity Address, State or Province | NJ |
| Entity Address, Postal Zip Code | 07701 |
| City Area Code | 732 |
| Local Phone Number | 240-4500 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common stock, $0.01 par value per share |
| Trading Symbol | OCFC |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001004702 |
| Amendment Flag | false |