Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Basic weighted average shares (in shares)										13,640,610	13,604,258	13,577,725
Net dilutive effect of share-based awards, treasury method (in shares)	[1]									650,924	646,405	546,335
Diluted weighted average shares (in shares)										14,291,534	14,250,663	14,124,060
Net income for the year										$ 2,898	$ 9,561	$ 26,153
Net income attributable to noncontrolling interest, net of tax										936	735	1,092
Net income attributable to Oppenheimer Holdings Inc.		$ (3,144)	$ (908)	$ 295	$ 5,719	$ 2,686	$ 4,470	$ (1,554)	$ 3,224	$ 1,962	$ 8,826	$ 25,061
Basic earnings (loss) per share (in dollars per share)		$ (0.23)	$ (0.07)	$ 0.02	$ 0.42	$ 0.20	$ 0.33	$ (0.11)	$ 0.24	$ 0.14	$ 0.65	$ 1.85
Diluted earnings (loss) per share (in dollars per share)		$ (0.23)	$ (0.07)	$ 0.02	$ 0.40	$ 0.19	$ 0.31	$ (0.11)	$ 0.23	$ 0.14	$ 0.62	$ 1.77
Class A Stock
Class of Stock [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)										5,309	43,008	57,573

[1] For the year ended December 31, 2015, the diluted earnings per share computation does not include the anti-dilutive effect of 5,309 shares of Class A Stock granted under share-based compensation arrangements (43,008 and 57,573 shares for the years ended December 31, 2014 and 2013, respectively).