Earnings Per Share - Summary of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Basic weighted average number of shares outstanding (in shares)		13,379,827	13,704,228
Net dilutive effect of share-based awards, treasury method (in shares)	[1]	0	578,042
Diluted weighted average number of shares outstanding (in shares)		13,379,827	14,282,270
Net income (loss) for the period		$ (3,909)	$ 6,121
Net income (loss) attributable to noncontrolling interest, net of tax		(62)	402
Net income (loss) attributable to Oppenheimer Holdings Inc.		$ (3,847)	$ 5,719
Basic earnings (loss) per share (in dollars per share)		$ (0.29)	$ 0.42
Diluted earnings (loss) per share (in dollars per share)		$ (0.29)	$ 0.40
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		1,295,972	46,076

[1] For the three months ended March 31, 2016, the diluted earnings per share computation does not include the anti-dilutive effect of 1,295,972 shares of Class A Stock granted under share-based compensation arrangements (46,076 for the three months ended March 31, 2015).