Supplemental Guarantor Condensed Consolidated Financial Statements - Condensed Consolidated Statements of Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
REVENUES
Commissions	$ 119,580	$ 125,634
Principal transactions, net	15,717	12,555
Interest	12,371	13,393
Investment banking	18,448	20,087
Advisory fees	56,720	50,077
Other	16,310	16,468
Total revenue	239,146	238,214
EXPENSES
Compensation and related expenses	159,209	158,651
Clearing and exchange fees	6,042	6,031
Communications and technology	15,864	16,138
Occupancy and equipment costs	17,565	24,344
Interest	6,862	8,792
Other	26,891	30,747
Total expenses	232,433	244,703
Income (loss) before income taxes	6,713	(6,489)
Income tax provision (benefit)	2,820	(2,606)
Net income (loss) for the period	3,893	(3,883)
Less net income attributable to non- controlling interest, net of tax	230	774
Net income (loss) attributable to Oppenheimer Holdings Inc.	3,663	(4,657)
Comprehensive income	451	(366)
Parent [Member]
REVENUES
Interest	5
Total revenue	5
EXPENSES
Compensation and related expenses	441	128
Communications and technology	23
Interest	4,375	4,374
Other	437	343
Total expenses	5,276	4,845
Income (loss) before income taxes	(5,271)	(4,845)
Income tax provision (benefit)	(2,032)	(1,832)
Net income (loss) for the period	(3,239)	(3,013)
Equity in subsidiaries	6,902	(1,644)
Net income (loss) attributable to Oppenheimer Holdings Inc.	3,663	(4,657)
Comprehensive income		2
Guarantor subsidiaries [Member]
REVENUES
Principal transactions, net	73	488
Interest	2,788	3,097
Other	42
Total revenue	2,903	3,585
EXPENSES
Occupancy and equipment costs		(42)
Interest		66
Other	3	18
Total expenses	3	42
Income (loss) before income taxes	2,900	3,543
Income tax provision (benefit)	679	1,233
Net income (loss) for the period	2,221	2,310
Net income (loss) attributable to Oppenheimer Holdings Inc.	2,221	2,310
Non-guarantor Subsidiaries [Member]
REVENUES
Commissions	119,580	125,634
Principal transactions, net	15,644	12,067
Interest	12,296	12,996
Investment banking	18,448	20,087
Advisory fees	57,360	50,714
Other	16,310	16,468
Total revenue	239,638	237,966
EXPENSES
Compensation and related expenses	158,768	158,523
Clearing and exchange fees	6,042	6,031
Communications and technology	15,841	16,138
Occupancy and equipment costs	17,607	24,386
Interest	5,205	7,052
Other	27,091	31,023
Total expenses	230,554	243,153
Income (loss) before income taxes	9,084	(5,187)
Income tax provision (benefit)	4,173	(2,007)
Net income (loss) for the period	4,911	(3,180)
Less net income attributable to non- controlling interest, net of tax	230	774
Net income (loss) attributable to Oppenheimer Holdings Inc.	4,681	(3,954)
Comprehensive income	451	(368)
Eliminations [Member]
REVENUES
Interest	(2,718)	(2,700)
Advisory fees	(640)	(637)
Other	(42)
Total revenue	(3,400)	(3,337)
EXPENSES
Occupancy and equipment costs	(42)
Interest	(2,718)	(2,700)
Other	(640)	(637)
Total expenses	(3,400)	(3,337)
Equity in subsidiaries	(6,902)	1,644
Net income (loss) attributable to Oppenheimer Holdings Inc.	$ (6,902)	$ 1,644