Supplemental Guarantor Condensed Consolidated Financial Statements - Condensed Consolidating Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
REVENUES
Commissions	$ 86,717	$ 103,833
Advisory fees	69,409	66,026
Investment banking	18,021	12,383
Interest	10,565	13,042
Principal transactions, net	5,373	6,618
Other	23,176	13,054
Total revenue	213,261	214,956
EXPENSES
Compensation and related expenses	143,878	148,495
Communications and technology	17,706	17,680
Occupancy and equipment costs	15,272	14,903
Clearing and exchange fees	5,854	6,921
Interest	5,356	4,867
Other	32,220	29,430
Total expenses	220,286	222,296
Loss before income taxes from continuing operations	(7,025)	(7,340)
Other Income Tax Expense (Benefit), Continuing Operations	(1,687)	(4,048)
Net loss from continuing operations	(5,338)	(3,292)
Income (loss) from discontinued operations	976	(657)
Equity in earnings of subsidiaries	0	0
Net loss	(4,751)	(3,909)
Income taxes	389	(40)
Net income (loss) from discontinued operations	587	(617)
Less net income (loss) attributable to noncontrolling interest, net of tax	96	(62)
Net loss attributable to Oppenheimer Holdings Inc.	(4,847)	(3,847)
Other comprehensive income	1,424	873
Total comprehensive loss	(3,423)	(2,974)
Eliminations
REVENUES
Commissions	0	0
Advisory fees	(320)	(353)
Investment banking	0	0
Interest	(2,576)	(2,567)
Principal transactions, net	0	0
Other	(88)	(78)
Total revenue	(2,984)	(2,998)
EXPENSES
Compensation and related expenses	0	0
Communications and technology	0	0
Occupancy and equipment costs	(88)	(78)
Clearing and exchange fees	0	0
Interest	(2,576)	(2,567)
Other	(320)	(353)
Total expenses	(2,984)	(2,998)
Loss before income taxes from continuing operations	0	0
Other Income Tax Expense (Benefit), Continuing Operations	0	0
Net loss from continuing operations	0	0
Income (loss) from discontinued operations	0	0
Equity in earnings of subsidiaries	6,479	4,042
Net loss	6,479	4,042
Income taxes	0	0
Net income (loss) from discontinued operations	0	0
Less net income (loss) attributable to noncontrolling interest, net of tax	0	0
Net loss attributable to Oppenheimer Holdings Inc.	6,479	4,042
Other comprehensive income	0	0
Total comprehensive loss	6,479	4,042
Guarantor Subsidiaries
REVENUES
Commissions	0	0
Advisory fees	0	0
Investment banking	0	0
Interest	2,579	2,557
Principal transactions, net	6	30
Other	88	78
Total revenue	2,673	2,665
EXPENSES
Compensation and related expenses	0	0
Communications and technology	0	0
Occupancy and equipment costs	0	0
Clearing and exchange fees	0	0
Interest	0	0
Other	72	3
Total expenses	72	3
Loss before income taxes from continuing operations	2,601	2,662
Other Income Tax Expense (Benefit), Continuing Operations	920	1,004
Net loss from continuing operations	1,681	1,658
Income (loss) from discontinued operations	0	0
Equity in earnings of subsidiaries	(4,080)	(2,850)
Net loss	(2,399)	(1,192)
Income taxes	0	0
Net income (loss) from discontinued operations	0	0
Less net income (loss) attributable to noncontrolling interest, net of tax	0	0
Net loss attributable to Oppenheimer Holdings Inc.	(2,399)	(1,192)
Other comprehensive income	0	0
Total comprehensive loss	(2,399)	(1,192)
Non-Guarantor Subsidiaries
REVENUES
Commissions	86,717	103,833
Advisory fees	69,729	66,379
Investment banking	18,021	12,383
Interest	10,562	13,052
Principal transactions, net	5,367	6,588
Other	23,176	13,054
Total revenue	213,572	215,289
EXPENSES
Compensation and related expenses	143,540	148,108
Communications and technology	17,676	17,652
Occupancy and equipment costs	15,360	14,981
Clearing and exchange fees	5,854	6,921
Interest	4,651	4,153
Other	32,141	29,107
Total expenses	219,222	220,922
Loss before income taxes from continuing operations	(5,650)	(5,633)
Other Income Tax Expense (Benefit), Continuing Operations	(1,079)	(3,338)
Net loss from continuing operations	(4,571)	(2,295)
Income (loss) from discontinued operations	976	(657)
Equity in earnings of subsidiaries	0	0
Net loss	(3,984)	(2,912)
Income taxes	389	(40)
Net income (loss) from discontinued operations	587	(617)
Less net income (loss) attributable to noncontrolling interest, net of tax	96	(62)
Net loss attributable to Oppenheimer Holdings Inc.	(4,080)	(2,850)
Other comprehensive income	1,424	873
Total comprehensive loss	(2,656)	(1,977)
Parent
REVENUES
Commissions	0	0
Advisory fees	0	0
Investment banking	0	0
Interest	0	0
Principal transactions, net	0	0
Other	0	0
Total revenue	0	0
EXPENSES
Compensation and related expenses	338	387
Communications and technology	30	28
Occupancy and equipment costs	0	0
Clearing and exchange fees	0	0
Interest	3,281	3,281
Other	327	673
Total expenses	3,976	4,369
Loss before income taxes from continuing operations	(3,976)	(4,369)
Other Income Tax Expense (Benefit), Continuing Operations	(1,528)	(1,714)
Net loss from continuing operations	(2,448)	(2,655)
Income (loss) from discontinued operations	0	0
Equity in earnings of subsidiaries	(2,399)	(1,192)
Net loss	(4,847)	(3,847)
Income taxes	0	0
Net income (loss) from discontinued operations	0	0
Less net income (loss) attributable to noncontrolling interest, net of tax	0	0
Net loss attributable to Oppenheimer Holdings Inc.	(4,847)	(3,847)
Other comprehensive income	0	0
Total comprehensive loss	$ (4,847)	$ (3,847)