Regulatory Matters - Summary of Regulatory Capital Amounts and Ratios (Details) $ in Thousands	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 capital (to average assets), Actual Ratio	0.040
Common equity Tier 1 (to risk-weighted assets), Actual Ratio	7.00%
Tier 1 capital (to average assets), For capital adequacy purposes Ratio	0.085
Total capital (to risk-weighted assets) For capital adequacy purposes Ratio	0.105
Capital conservation buffer (as a percent)	0.0250
OceanFirst Financial Corp.
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 capital (to average assets), Actual Amount	$ 1,150,690	$ 1,044,518
Common equity Tier 1 (to risk-weighted asset), Actual Amount	1,021,774	917,088
Tier 1 capital (to risk-weighted assets), Actual Amount	1,150,690	1,044,518
Total capital (to risk-weighted assets), Actual Amount	$ 1,336,652	$ 1,257,372
Tier 1 capital (to average assets), Actual Ratio	0.0943	0.0922
Common equity Tier 1 (to risk-weighted assets), Actual Ratio	9.93%	10.26%
Tier 1 capital (to risk-weighted assets), Actual Ratio	0.1118	0.1168
Total capital (to risk-weighted assets), Actual Ratio	0.1298	0.1406
Tier 1 capital (to average assets), For capital adequacy purposes Amount	$ 488,297	$ 453,087
Common equity Tier 1 (to risk-weighted asset), For capital adequacy purposes Amount	720,641	625,801
Tier 1 capital (to risk-weighted assets), For capital adequacy purposes Amount	875,064	759,902
Total capital (to risk-weighted assets), For capital adequacy purposes Amount	$ 1,080,961	$ 938,702
Tier 1 capital (to average assets), For capital adequacy purposes Ratio	0.0400	0.0400
Common equity Tier 1 (to risk-weighted assets), For capital adequacy purposes Ratio	7.00%	7.00%
Tier 1 capital (to risk-weighted assets), For capital adequacy purposes Ratio	0.0850	0.0850
Total capital (to risk-weighted assets) For capital adequacy purposes Ratio	0.1050	0.1050
OceanFirst Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 capital (to average assets), Actual Amount	$ 1,122,946	$ 1,027,660
Common equity Tier 1 (to risk-weighted asset), Actual Amount	1,122,946	1,027,660
Tier 1 capital (to risk-weighted assets), Actual Amount	1,122,946	1,027,660
Total capital (to risk-weighted assets), Actual Amount	$ 1,183,705	$ 1,079,766
Tier 1 capital (to average assets), Actual Ratio	0.0920	0.0908
Common equity Tier 1 (to risk-weighted assets), Actual Ratio	11.02%	11.62%
Tier 1 capital (to risk-weighted assets), Actual Ratio	0.1102	0.1162
Total capital (to risk-weighted assets), Actual Ratio	0.1162	0.1221
Tier 1 capital (to average assets), For capital adequacy purposes Amount	$ 488,033	$ 452,669
Common equity Tier 1 (to risk-weighted asset), For capital adequacy purposes Amount	713,194	619,178
Tier 1 capital (to risk-weighted assets), For capital adequacy purposes Amount with buffer	866,021	751,860
Total capital (to risk-weighted assets), For capital adequacy purposes Amount	$ 1,069,791	$ 928,768
Tier 1 capital (to average assets), For capital adequacy purposes Ratio	0.0400	0.0400
Common equity Tier 1 (to risk-weighted assets), For capital adequacy purposes Ratio	7.00%	7.00%
Tier 1 capital (to risk-weighted assets), For capital adequacy purposes Ratio with buffer	0.0850	0.0850
Total capital (to risk-weighted assets) For capital adequacy purposes Ratio	0.1050	0.1050
Tier 1 capital (to average assets), To be well capitalized under Prompt Corrective Action Amount	$ 610,041	$ 565,836
Common equity Tier 1 (to risk-weighted asset), To be well capitalized under Prompt Corrective Action Amount	662,251	574,951
Tier 1 capital (to risk-weighted assets), To be well capitalized under Prompt Corrective Action Amount	815,078	707,633
Total capital (to risk-weighted assets), To be well capitalized under Prompt Corrective Action Amount	$ 1,018,848	$ 884,541
Tier 1 capital (to average assets), To be well capitalized under Prompt Corrective Action Ratio	0.0500	0.0500
Common equity Tier 1 (to risk-weighted asset), To be well capitalized under Prompt Corrective Action Ratio	6.50%	6.50%
Tier 1 capital (to risk-weighted assets), To be well capitalized under Prompt Corrective Action Ratio	0.0800	0.0800
Total capital (to risk-weighted assets), To be well capitalized under Prompt Corrective Action Ratio	0.1000	0.1000