Condensed Consolidating Financial Information - Condensed Consolidating Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015		Sep. 30, 2016	Sep. 30, 2015
REVENUES
Commissions	$ 90,023	$ 101,243	[1]	$ 286,447	$ 314,494	[1]
Advisory fees	67,452	69,557	[1]	199,582	212,766	[1]
Investment banking	20,280	16,548	[1]	51,544	72,873	[1]
Interest	11,291	13,759	[1]	36,340	35,775	[1]
Principal transactions, net	4,922	2,309	[1]	19,117	14,347	[1]
Other	17,836	4,062	[1]	45,804	22,357	[1]
Total revenue	211,804	207,478	[1]	638,834	672,612	[1]
EXPENSES
Compensation and related expenses	142,308	139,314	[1]	432,524	453,943	[1]
Communications and technology	17,201	16,396	[1]	52,519	49,775	[1]
Occupancy and equipment costs	14,909	16,083	[1]	44,796	47,695	[1]
Clearing and exchange fees	5,886	6,909	[1]	19,006	19,542	[1]
Interest	4,687	4,228	[1]	14,526	12,103	[1]
Other	28,623	27,121	[1]	89,859	87,414	[1]
Total expenses	213,614	210,051	[1]	653,230	670,472	[1]
Income (loss) before income taxes	(1,810)	(2,573)	[1]	(14,396)	2,140	[1]
Income taxes	(751)	(1,437)	[1]	(7,190)	1,118	[1]
Net income (loss) from continuing operations	(1,059)	(1,136)	[1]	(7,206)	1,022	[1]
Income attributable to noncontrolling interest before income taxes	888	1,046	[1]	15,597	8,814	[1]
Tax effect of discontinued operation	475	687	[1]	6,235	3,847	[1]
Net income from discontinued operations	413	359	[1]	9,362	4,967	[1]
Equity in earnings of subsidiaries	0	0		0	0
Net income (loss)	(646)	(777)	[1]	2,156	5,989	[1]
Less net income attributable to noncontrolling interests	66	131	[1]	1,527	883	[1]
Net income (loss) attributable to Oppenheimer Holdings Inc.	(712)	(908)	[1]	629	5,106	[1]
Other comprehensive income (loss)	681	(916)		900	(166)
Comprehensive income (loss) attributable to Oppenheimer Holdings Inc.	(31)	(1,824)		1,529	4,940
Eliminations [Member]
REVENUES
Commissions	0	0		0	0
Advisory fees	(437)	(381)		(1,197)	(1,246)
Investment banking	0	0		0	0
Interest	(2,692)	(2,565)		(7,824)	(7,694)
Principal transactions, net	0	(239)		0	(323)
Other	(81)	(74)		(239)	(225)
Total revenue	(3,210)	(3,259)		(9,260)	(9,488)
EXPENSES
Compensation and related expenses	0	0		0	0
Communications and technology	0	0		0	0
Occupancy and equipment costs	(81)	(74)		(239)	(225)
Clearing and exchange fees	0	0		0	0
Interest	(2,692)	(2,565)		(7,824)	(7,694)
Other	(437)	(620)		(1,197)	(1,569)
Total expenses	(3,210)	(3,259)		(9,260)	(9,488)
Income (loss) before income taxes	0	0		0	0
Income taxes	0	0		0	0
Net income (loss) from continuing operations	0	0		0	0
Income attributable to noncontrolling interest before income taxes	0	0		0	0
Tax effect of discontinued operation	0	0		0	0
Net income from discontinued operations	0	0		0	0
Equity in earnings of subsidiaries	(51)	(2,051)		(6,573)	(20,146)
Net income (loss)	(51)	(2,051)		(6,573)	(20,146)
Less net income attributable to noncontrolling interests	0	0		0	0
Net income (loss) attributable to Oppenheimer Holdings Inc.	(51)	(2,051)		(6,573)	(20,146)
Other comprehensive income (loss)	0	0		0	0
Comprehensive income (loss) attributable to Oppenheimer Holdings Inc.	(51)	(2,051)		(6,573)	(20,146)
Parent Company [Member]
REVENUES
Commissions	0	0		0	0
Advisory fees	0	0		0	0
Investment banking	0	0		0	0
Interest	0	0		0	0
Principal transactions, net	0	0		0	0
Other	0	0		0	0
Total revenue	0	0		0	0
EXPENSES
Compensation and related expenses	251	254		994	829
Communications and technology	30	27		92	94
Occupancy and equipment costs	0	0		0	0
Clearing and exchange fees	0	0		0	0
Interest	3,281	3,282		9,844	9,844
Other	310	234		1,506	780
Total expenses	3,872	3,797		12,436	11,547
Income (loss) before income taxes	(3,872)	(3,797)		(12,436)	(11,547)
Income taxes	(2,018)	(1,343)		(7,004)	(4,344)
Net income (loss) from continuing operations	(1,854)	(2,454)		(5,432)	(7,203)
Income attributable to noncontrolling interest before income taxes	0	0		0	0
Tax effect of discontinued operation	0	0		0	0
Net income from discontinued operations	0	0		0	0
Equity in earnings of subsidiaries	1,142	1,546		6,061	12,309
Net income (loss)	(712)	(908)		629	5,106
Less net income attributable to noncontrolling interests	0	0		0	0
Net income (loss) attributable to Oppenheimer Holdings Inc.	(712)	(908)		629	5,106
Other comprehensive income (loss)	0	0		0	0
Comprehensive income (loss) attributable to Oppenheimer Holdings Inc.	(712)	(908)		629	5,106
Guarantor Subsidiaries [Member]
REVENUES
Commissions	0	0		0	0
Advisory fees	0	0		0	0
Investment banking	0	0		0	0
Interest	2,556	2,557		7,669	7,680
Principal transactions, net	1	0		53	0
Other	81	96		240	287
Total revenue	2,638	2,653		7,962	7,967
EXPENSES
Compensation and related expenses	0	0		0	0
Communications and technology	0	0		0	0
Occupancy and equipment costs	0	0		0	0
Clearing and exchange fees	0	0		0	0
Interest	0			0	0
Other	3	252		8	365
Total expenses	3	252		8	365
Income (loss) before income taxes	2,635	2,401		7,954	7,602
Income taxes	402	1,360		2,405	3,130
Net income (loss) from continuing operations	2,233	1,041		5,549	4,472
Income attributable to noncontrolling interest before income taxes	0	0		0	0
Tax effect of discontinued operation	0	0		0	0
Net income from discontinued operations	0	0		0	0
Equity in earnings of subsidiaries	(1,091)	505		512	7,837
Net income (loss)	1,142	1,546		6,061	12,309
Less net income attributable to noncontrolling interests	0	0		0	0
Net income (loss) attributable to Oppenheimer Holdings Inc.	1,142	1,546		6,061	12,309
Other comprehensive income (loss)	0	0		0	0
Comprehensive income (loss) attributable to Oppenheimer Holdings Inc.	1,142	1,546		6,061	12,309
Non-Guarantor Subsidiaries [Member]
REVENUES
Commissions	90,023	101,243		286,447	314,494
Advisory fees	67,889	69,938		200,779	214,012
Investment banking	20,280	16,548		51,544	72,873
Interest	11,427	13,767		36,495	35,789
Principal transactions, net	4,921	2,548		19,064	14,670
Other	17,836	4,040		45,803	22,295
Total revenue	212,376	208,084		640,132	674,133
EXPENSES
Compensation and related expenses	142,057	139,060		431,530	453,114
Communications and technology	17,171	16,369		52,427	49,681
Occupancy and equipment costs	14,990	16,157		45,035	47,920
Clearing and exchange fees	5,886	6,909		19,006	19,542
Interest	4,098	3,511		12,506	9,953
Other	28,747	27,255		89,542	87,838
Total expenses	212,949	209,261		650,046	668,048
Income (loss) before income taxes	(573)	(1,177)		(9,914)	6,085
Income taxes	865	(1,454)		(2,591)	2,332
Net income (loss) from continuing operations	(1,438)	277		(7,323)	3,753
Income attributable to noncontrolling interest before income taxes	888	1,046		15,597	8,814
Tax effect of discontinued operation	475	687		6,235	3,847
Net income from discontinued operations	413	359		9,362	4,967
Equity in earnings of subsidiaries	0	0		0	0
Net income (loss)	(1,025)	636		2,039	8,720
Less net income attributable to noncontrolling interests	66	131		1,527	883
Net income (loss) attributable to Oppenheimer Holdings Inc.	(1,091)	505		512	7,837
Other comprehensive income (loss)	681	(916)		900	(166)
Comprehensive income (loss) attributable to Oppenheimer Holdings Inc.	$ (410)	$ (411)		$ 1,412	$ 7,671

[1] Amounts have been recast to reflect discontinued operations. See Note 3 for details.