CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY AND NONCONTROLLING INTERESTS (unaudited) - USD ($) $ in Thousands	Total	Parent	Common Stock	Common Stock Class A Stock	Additional paid-in capital	Additional paid-in capital Class A Stock	Retained earnings		Retained earnings Class A Stock	Accumulated other comprehensive income (loss)	Noncontrolling interest
Balance at beginning of period at Dec. 31, 2023			$ 10		$ 31,774		$ 756,468			$ 914	$ 73
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A non-voting common stock				$ 0		$ 8,409
Repurchase of Class A non-voting common stock for cancellation				0		(8,384)			$ (924)
Share-based expense					6,470
Vested employee share plan awards					(15,168)
Change in redemption value of redeemable noncontrolling interests					264
Net income (loss)	$ 36,010						36,320	[1]			(310)
Dividends paid							(3,125)
Currency translation adjustment	(967)									(968)
Capital addition to noncontrolling interest											237
Balance at end of period at Jun. 30, 2024	$ 812,060	$ 812,060	10		23,365		788,739			(54)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends paid per share (in dollars per share)	$ 0.30
Balance at beginning of period at Dec. 31, 2023			10		31,774		756,468			914	73
Balance at end of period at Dec. 31, 2024			10		29,733		819,961			691	0
Balance at beginning of period at Mar. 31, 2024			10		20,040		780,946			526	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A non-voting common stock				0		171
Repurchase of Class A non-voting common stock for cancellation				0		0			(924)
Share-based expense					3,325
Vested employee share plan awards					(171)
Change in redemption value of redeemable noncontrolling interests					0
Net income (loss)	$ 10,266						10,266	[1]			0
Dividends paid							(1,549)
Currency translation adjustment	(580)									(580)
Capital addition to noncontrolling interest											0
Balance at end of period at Jun. 30, 2024	$ 812,060	812,060	10		23,365		788,739			(54)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends paid per share (in dollars per share)	$ 0.15
Balance at beginning of period at Dec. 31, 2024			10		29,733		819,961			691	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A non-voting common stock				0		6,276
Repurchase of Class A non-voting common stock for cancellation				0		(90)			(580)
Share-based expense					6,778
Vested employee share plan awards					(16,121)
Change in redemption value of redeemable noncontrolling interests					0
Net income (loss)	$ 52,329						52,329	[1]			0
Dividends paid							(3,788)
Currency translation adjustment	1,659									1,659
Capital addition to noncontrolling interest											0
Balance at end of period at Jun. 30, 2025	$ 896,858	896,858	10		26,576		867,922			2,350	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends paid per share (in dollars per share)	$ 0.36
Balance at beginning of period at Mar. 31, 2025			10		23,331		848,721			204	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A non-voting common stock				0		77
Repurchase of Class A non-voting common stock for cancellation				$ 0		$ 0			$ (580)
Share-based expense					3,320
Vested employee share plan awards					(152)
Change in redemption value of redeemable noncontrolling interests					0
Net income (loss)	$ 21,674						21,674	[1]			0
Dividends paid							(1,893)
Currency translation adjustment	2,146									2,146
Capital addition to noncontrolling interest											0
Balance at end of period at Jun. 30, 2025	$ 896,858	$ 896,858	$ 10		$ 26,576		$ 867,922			$ 2,350	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends paid per share (in dollars per share)	$ 0.18

[1] (1) Attributable to Oppenheimer Holdings Inc.