Earnings Per Share - Summary of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Basic weighted average number of shares outstanding										13,368,768	13,640,610	13,604,258
Net dilutive effect of share-based awards, treasury method	[1]									0	0	646,405
Diluted weighted average number of shares outstanding										13,368,768	13,640,610	14,250,663
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest		$ (2,424)	$ (1,059)	$ (2,619)	$ (3,528)	$ (3,856)	$ (1,136)	$ (1,501)	$ 3,659	$ (9,630)	$ (2,834)	$ 5,056
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest		759	413	9,330	(381)	765	359	2,146	2,462	10,121	5,732	4,505
Net income		(1,665)	(646)	6,711	(3,909)	(3,091)	(777)	645	6,121	491	2,898	9,561
Net income attributable to non-controlling interest, net of tax		125	66	1,523	(62)	53	131	350	402	1,652	936	735
Net income (loss) attributable to Oppenheimer Holdings Inc.		$ (1,790)	$ (712)	$ 5,188	$ (3,847)	$ (3,144)	$ (908)	$ 295	$ 5,719	$ (1,161)	$ 1,962	$ 8,826
Income (Loss) from Continuing Operations, Per Basic Share		$ (0.28)	$ (0.08)	$ (0.20)	$ (0.27)	$ (0.28)	$ (0.08)	$ (0.11)	$ 0.27	$ (0.72)	$ (0.21)	$ 0.37
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share		0.05	0.03	0.59	(0.02)	0.05	0.01	0.13	0.15	0.63	0.35	0.28
Net income (loss) per share		(0.23)	(0.05)	0.39	(0.29)	0	0	0	0	(0.09)	0.14	0.65
Income (Loss) from Continuing Operations, Per Diluted Share		(0.28)	(0.08)	(0.20)	(0.27)	(0.28)	(0.08)	(0.11)	0.26	(0.72)	(0.21)	0.36
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share		0.05	0.03	0.59	(0.02)	0.05	0.01	0.13	0.14	0.63	0.35	0.26
Diluted earnings per share		$ (0.23)	$ (0.05)	$ 0.39	$ (0.29)	$ 0	$ 0	$ 0	$ 0	$ (0.09)	$ 0.14	$ 0.62

[1] For the year ended December 31, 2016, the diluted earnings per share computation does not include the anti-dilutive effect of 1,237,134 shares of Class A Stock granted under share-based compensation arrangements (1,269,585 and 43,008 shares for the years ended December 31, 2015 and 2014, respectively).(2)Represents net income from discontinued operations less net income attributable to noncontrolling interest, net of tax divided by weighted average number of shares outstanding.