Parent-Only Financial Information - Schedule of Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net income	$ 104,065	$ 147,357	$ 110,076
Net loss (gain) on equity investments	3,732	(9,685)	(7,145)
Net premium amortization in excess of discount accretion on securities	3,133	7,164	8,466
Amortization of deferred costs on borrowings	598	548	824
Net amortization of purchase accounting adjustments	(5,848)	(9,752)	(14,484)
Net cash provided by operating activities	124,261	250,450	159,972
Cash flows from investing activities:
Proceeds from sales of equity investments	4,822	19,234	98,777
Purchase of equity investments	(7,661)	(9,366)	(86,462)
Net cash used in investing activities	(487,997)	(1,321,008)	(1,477,842)
Cash flows from financing activities:
Repayments of other borrowings	0	(35,104)	(7,612)
Dividends paid	(51,274)	(47,511)	(44,510)
Purchase of treasury stock	0	(7,396)	(36,059)
Exercise of stock options	702	424	1,946
Distributions to non-controlling interest	(55)	(782)	0
Net cash provided by financing activities	349,468	1,013,760	223,993
Net decrease in cash and due from banks and restricted cash	(14,268)	(56,798)	(1,093,877)
Cash and due from banks at beginning of year	167,946	204,949	1,272,134
Cash and due from banks at end of year	153,718	167,946	204,949
OceanFirst Financial Corp.
Cash flows from operating activities:
Net income	104,065	147,357	110,076
(Increase) decrease in advances to subsidiary Bank	(34,449)	30,640	37,824
Undistributed earnings of subsidiary Bank	(19,220)	(77,357)	(73,311)
Net loss (gain) on equity investments	3,732	(7,973)	(7,499)
Net premium amortization in excess of discount accretion on securities	981	1,185	755
Amortization of deferred costs on borrowings	598	548	824
Net amortization of purchase accounting adjustments	704	684	542
Change in other assets and other liabilities	(3,995)	2,336	7,359
Net cash provided by operating activities	52,416	97,420	76,570
Cash flows from investing activities:
Proceeds from sales of equity investments	4,822	6,482	98,791
Purchase of equity investments	(7,661)	(7,207)	(86,462)
Increase in ESOP loan receivable	0	0	(3,200)
Repayments on ESOP loan receivable	2,510	2,480	2,040
Cash consideration for acquisition, net of cash received	0	(7,084)	0
Net cash used in investing activities	(329)	(5,329)	11,169
Cash flows from financing activities:
Repayments of other borrowings	0	(35,000)	(7,500)
Dividends paid	(51,274)	(47,511)	(44,510)
Purchase of treasury stock	0	(7,396)	(36,059)
Exercise of stock options	702	424	1,946
Distributions to non-controlling interest	(55)	(788)	0
Net cash provided by financing activities	(50,627)	(90,271)	(86,123)
Net decrease in cash and due from banks and restricted cash	1,460	1,820	1,616
Cash and due from banks at beginning of year	10,623	8,803	7,187
Cash and due from banks at end of year	$ 12,083	$ 10,623	$ 8,803