Parent-Only Financial Information - Condensed Statements of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Condensed Financial Statements, Captions [Line Items]
Net gain on equity investments	$ 9,685	$ 7,145	$ 21,214
Interest expense – borrowings	22,677	11,544	18,367
Operating expenses	234,881	226,860	246,431
Benefit (provision) for income taxes	(46,565)	(32,165)	(17,733)
Net income	147,357	110,076	63,309
Net income attributable to non-controlling interest	754	0	0
Net income attributable to OceanFirst Financial Corp.	146,603	110,076	63,309
OceanFirst Financial Corp.
Condensed Financial Statements, Captions [Line Items]
Dividend income – subsidiaries	73,011	40,000	54,000
Interest and dividend income – debt and equity securities	2,387	2,070	949
Interest income – advances to subsidiary Bank	562	298	403
Interest income – ESOP loan receivable	227	289	301
Net gain on equity investments	7,973	7,499	20,460
Total income	84,160	50,156	76,113
Interest expense – borrowings	10,861	11,102	10,592
Operating expenses	4,258	3,307	3,382
Income before income taxes and undistributed earnings of subsidiaries	69,041	35,747	62,139
Benefit (provision) for income taxes	959	1,018	(2,901)
Income before undistributed earnings of subsidiaries	70,000	36,765	59,238
Undistributed earnings of subsidiaries	77,357	73,311	4,071
Net income	147,357	110,076	63,309
Net income attributable to non-controlling interest	754	0	0
Net income attributable to OceanFirst Financial Corp.	$ 146,603	$ 110,076	$ 63,309