Condensed Consolidating Financial Information - Condensed Consolidating Statement of Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
REVENUES
Commissions	$ 116,062	$ 124,440	$ 238,200	$ 244,020
Advisory fees	70,430	60,580	138,635	117,300
Investment banking	26,799	22,567	60,323	41,015
Interest	12,548	13,106	24,938	25,477
Principal transactions, net	11,794	7,532	20,611	23,249
Other	12,056	15,605	22,150	31,915
Total revenue	249,689	243,830	504,857	482,976
EXPENSES
Compensation and related expenses	159,851	160,006	331,801	319,215
Communications and technology	17,536	16,018	34,270	31,882
Occupancy and equipment costs	15,907	17,141	31,304	34,706
Clearing and exchange fees	6,024	6,293	11,916	12,335
Interest	4,412	7,143	9,576	14,005
Other	45,823	31,555	80,745	58,446
Total expenses	249,553	238,156	499,612	470,589
Income (loss) before income taxes	136	5,674	5,245	12,387
Income tax provision (benefit)	1,389	2,608	3,078	5,428
Net income (loss) for the period	(1,253)	3,066	2,167	6,959
Less net income attributable to non-controlling interests, net of tax	301	218	497	448
Net income (loss) attributable to Oppenheimer Holdings Inc.	(1,554)	2,848	1,670	6,511
Other comprehensive income (loss)	339	49	252	500
Comprehensive income (loss) attributable to Oppenheimer Holdings Inc.	(1,215)	2,897	1,922	7,011
Eliminations [Member]
REVENUES
Advisory fees	(311)	(547)	(681)	(1,187)
Interest	(2,586)	(2,717)	(5,296)	(5,435)
Other	(64)	(42)	(280)	(84)
Total revenue	(2,961)	(3,306)	(6,257)	(6,706)
EXPENSES
Occupancy and equipment costs	(64)	(42)	(280)	(84)
Interest	(2,586)	(2,717)	(5,296)	(5,435)
Other	(311)	(547)	(681)	(1,187)
Total expenses	(2,961)	(3,306)	(6,257)	(6,706)
Equity in subsidiaries	(3,350)	(5,936)	(9,724)	(12,838)
Net income (loss) attributable to Oppenheimer Holdings Inc.	(3,350)	(5,936)	(9,724)	(12,838)
Comprehensive income (loss) attributable to Oppenheimer Holdings Inc.	(3,350)	(5,936)	(9,724)	(12,838)
Parent Company [Member]
REVENUES
Interest		0		5
Total revenue		0		5
EXPENSES
Compensation and related expenses	300	254	615	695
Communications and technology	47	35	74	58
Interest	3,464	4,375	7,839	8,750
Other	3,817	323	4,161	760
Total expenses	7,628	4,987	12,689	10,263
Income (loss) before income taxes	(7,628)	(4,987)	(12,689)	(10,258)
Income tax provision (benefit)	(2,723)	(1,899)	(4,634)	(3,931)
Net income (loss) for the period	(4,905)	(3,088)	(8,055)	(6,327)
Equity in subsidiaries	3,350	5,936	9,724	12,838
Net income (loss) attributable to Oppenheimer Holdings Inc.	(1,555)	2,848	1,669	6,511
Other comprehensive income (loss)		(3)		(3)
Comprehensive income (loss) attributable to Oppenheimer Holdings Inc.	(1,555)	2,845	1,669	6,508
Guarantor Subsidiaries [Member]
REVENUES
Interest	2,588	2,805	5,321	5,593
Principal transactions, net	131	(61)	171	12
Other	74	42	290	84
Total revenue	2,793	2,786	5,782	5,689
EXPENSES
Other	11	16	13	19
Total expenses	11	16	13	19
Income (loss) before income taxes	2,782	2,770	5,769	5,670
Income tax provision (benefit)	1,269	1,215	1,131	1,894
Net income (loss) for the period	1,513	1,555	4,638	3,776
Net income (loss) attributable to Oppenheimer Holdings Inc.	1,513	1,555	4,638	3,776
Comprehensive income (loss) attributable to Oppenheimer Holdings Inc.	1,513	1,555	4,638	3,776
Non-Guarantor Subsidiaries [Member]
REVENUES
Commissions	116,062	124,440	238,200	244,020
Advisory fees	70,741	61,127	139,316	118,487
Investment banking	26,799	22,567	60,323	41,015
Interest	12,546	13,018	24,913	25,314
Principal transactions, net	11,663	7,593	20,440	23,237
Other	12,046	15,605	22,140	31,915
Total revenue	249,857	244,350	505,332	483,988
EXPENSES
Compensation and related expenses	159,551	159,752	331,186	318,520
Communications and technology	17,489	15,983	34,196	31,824
Occupancy and equipment costs	15,971	17,183	31,584	34,790
Clearing and exchange fees	6,024	6,293	11,916	12,335
Interest	3,534	5,485	7,033	10,690
Other	42,306	31,763	77,252	58,854
Total expenses	244,875	236,459	493,167	467,013
Income (loss) before income taxes	4,982	7,891	12,165	16,975
Income tax provision (benefit)	2,843	3,292	6,581	7,465
Net income (loss) for the period	2,139	4,599	5,584	9,510
Less net income attributable to non-controlling interests, net of tax	301	218	497	448
Net income (loss) attributable to Oppenheimer Holdings Inc.	1,838	4,381	5,087	9,062
Other comprehensive income (loss)	339	52	252	503
Comprehensive income (loss) attributable to Oppenheimer Holdings Inc.	$ 2,177	$ 4,433	$ 5,339	$ 9,565