Earnings Per Share - Summary of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Basic weighted average number of shares outstanding (in shares)		13,745,957	13,618,174	13,725,208	13,577,714
Net dilutive effect of share-based awards, treasury method	[1]	644,623	0	617,266	606,616
Diluted weighted average number of shares outstanding		14,390,580	13,618,174	14,342,474	14,184,330
Net income (loss) for the period		$ 645	$ (1,253)	$ 6,766	$ 2,167
Net income attributable to noncontrolling interest, net of tax		350	301	752	497
Net income (loss) attributable to Oppenheimer Holdings Inc.		$ 295	$ (1,554)	$ 6,014	$ 1,670
Basic earnings (loss) per share (in dollars per share)		$ 0.02	$ (0.11)	$ 0.44	$ 0.12
Diluted earnings (loss) per share (in dollars per share)		$ 0.02	$ (0.11)	$ 0.42	$ 0.12
Class A Stock [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Number of anti-dilutive warrants, options and restricted shares, for the year		37,333	1,381,907	40,309	58,008

[1] For the three and six months ended June 30, 2015, the diluted earnings per share computation does not include the anti-dilutive effect of 37,333 and 40,309 shares of Class A Stock granted under share-based compensation arrangements, respectively (1,381,907 and 58,008, respectively, for the three and six months ended June 30, 2014).