Regulatory Matters - Schedule of Regulatory Capital Amounts and Ratios (Details) $ in Thousands	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
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	0.0250
OceanFirst Financial Corp.
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 capital (to average assets), Actual Amount	$ 1,218,142	$ 1,150,690
Common equity Tier 1 (to risk-weighted asset), Actual Amount	1,088,542	1,021,774
Tier 1 capital (to risk-weighted assets), Actual Amount	1,218,142	1,150,690
Total capital (to risk-weighted assets), Actual Amount	$ 1,413,400	$ 1,336,652
Tier 1 capital (to average assets), Actual Ratio	0.0931	0.0943
Common equity Tier 1 (to risk-weighted assets), Actual Ratio	10.86%	9.93%
Tier 1 capital (to risk-weighted assets), Actual Ratio	0.1215	0.1118
Total capital (to risk-weighted assets), Actual Ratio	0.1410	0.1298
Tier 1 capital (to average assets), For capital adequacy purposes Amount	$ 523,588	$ 488,297
Common equity Tier 1 (to risk-weighted asset), For capital adequacy purposes Amount	701,778	720,641
Tier 1 capital (to risk-weighted assets), For capital adequacy purposes Amount	852,159	875,064
Total capital (to risk-weighted assets), For capital adequacy purposes Amount	$ 1,052,667	$ 1,080,961
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	$ 1,155,896	$ 1,122,946
Common equity Tier 1 (to risk-weighted asset), Actual Amount	1,155,896	1,122,946
Tier 1 capital (to risk-weighted assets), Actual Amount	1,155,896	1,122,946
Total capital (to risk-weighted assets), Actual Amount	$ 1,226,154	$ 1,183,705
Tier 1 capital (to average assets), Actual Ratio	0.0890	0.0920
Common equity Tier 1 (to risk-weighted assets), Actual Ratio	11.65%	11.02%
Tier 1 capital (to risk-weighted assets), Actual Ratio	0.1165	0.1102
Total capital (to risk-weighted assets), Actual Ratio	0.1236	0.1162
Tier 1 capital (to average assets), For capital adequacy purposes Amount	$ 519,690	$ 488,033
Common equity Tier 1 (to risk-weighted asset), For capital adequacy purposes Amount	694,620	713,194
Tier 1 capital (to risk-weighted assets), For capital adequacy purposes Amount with buffer	843,467	866,021
Total capital (to risk-weighted assets), For capital adequacy purposes Amount	$ 1,041,930	$ 1,069,791
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	$ 649,612	$ 610,041
Common equity Tier 1 (to risk-weighted asset), To be well-capitalized under Prompt Corrective Action Amount	645,004	662,251
Tier 1 capital (to risk-weighted assets), To be well-capitalized under Prompt Corrective Action Amount	793,852	815,078
Total capital (to risk-weighted assets), To be well-capitalized under Prompt Corrective Action Amount	$ 992,315	$ 1,018,848
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