Earnings Per Share - Summary of Earnings Per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Earnings Per Share [Abstract]
Basic weighted average number of shares outstanding (in shares)	13,618,174		13,607,348		13,577,714		13,607,671
Net dilutive effect of share-based awards, treasury method	0	[1]	461,020	[1]	606,616	[1]	461,108	[1]
Diluted weighted average number of shares outstanding (in shares)	13,618,174		14,068,368		14,184,330		14,068,779
Net income (loss) for the period	$ (1,253)		$ 3,066		$ 2,167		$ 6,959
Net income attributable to non-controlling interest, net of tax	301		218		497		448
Net income (loss) attributable to Oppenheimer Holdings Inc.	$ (1,554)		$ 2,848		$ 1,670		$ 6,511
Basic earnings (loss) per share (in dollars per share)	$ (0.11)		$ 0.21		$ 0.12		$ 0.48
Diluted earnings (loss) per share (in dollars per share)	$ (0.11)		$ 0.20		$ 0.12		$ 0.46

[1] For the three and six months ended June 30, 2014, the diluted earnings per share computation does not include the anti-dilutive effect of 1,381,907 and 58,008 shares of Class A Stock granted under share-based compensation arrangements, respectively (57,573 shares of Class A Stock granted under share-based compensation arrangements for the three and six months ended June 30, 2013).