Earnings Per Share - Summary of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015		Sep. 30, 2016	Sep. 30, 2015
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income (loss) from continuing operations		$ (1,059)	$ (1,136)	[1]	$ (7,206)	$ 1,022	[1]
Net income from discontinued operations		413	359	[1]	9,362	4,967	[1]
Net income (loss)		(646)	(777)	[1]	2,156	5,989	[1]
Less net income attributable to noncontrolling interest, net of tax		66	131	[1]	1,527	883	[1]
Net income (loss) attributable to Oppenheimer Holdings Inc.		$ (712)	$ (908)	[1]	$ 629	$ 5,106	[1]
Basic weighted average number of shares outstanding (in shares)		13,366,863	13,690,698	[1]	13,371,296	13,713,578	[1]
Net dilutive effect of share-based awards, treasury method (in shares)	[2]	0	0		0	625,627
Diluted weighted average number of shares outstanding (in shares)		13,366,863	13,690,698	[1]	13,371,296	14,339,205	[1]
Basic earnings (loss) per share attributable to Oppenheimer Holdings Inc.
Continuing operations, basic (in dollars per share)		$ (0.08)	$ (0.08)	[1]	$ (0.54)	$ 0.07	[1]
Discontinued operations, basic (in dollars per share)		0.03	0.01	[1]	0.59	0.30	[1]
Basic (in dollars per share)		(0.05)	(0.07)	[1]	0.05	0.37	[1]
Diluted earnings (loss) per share attributable to Oppenheimer Holdings Inc.
Continuing operations, diluted (in dollars per share)		(0.08)	(0.08)	[1]	(0.54)	0.07	[1]
Discontinued operations, diluted (in dollars per share)		0.03	0.01	[1]	0.59	0.29	[1]
Diluted (in dollars per share)		$ (0.05)	$ (0.07)	[1]	$ 0.05	$ 0.36	[1]
Class A Stock [Member]
Diluted earnings (loss) per share attributable to Oppenheimer Holdings Inc.
Number of anti-dilutive warrants, options and restricted shares, for the year (in shares)		1,249,063	1,304,185		1,249,063	40,309

[1] Amounts have been recast to reflect discontinued operations. See Note 3 for details.

[2] For both the three and nine months ended September 30, 2016, the diluted earnings (loss) per share computation does not include the anti-dilutive effect of 1,249,063 shares of Class A Stock granted under share-based compensation arrangements (1,304,185 and 40,309, respectively, for the three and nine months ended September 30, 2015).