Quarterly Information - Schedule of Quarterly Information (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
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 218,945		$ 211,804		$ 212,074		$ 214,956		$ 225,189		$ 207,478		$ 227,959		$ 237,175		$ 857,779		$ 897,801		$ 981,135
Operating Expenses	226,441		213,614		217,320		222,296		229,757		210,051		229,060		231,361		879,671		900,229		963,945
Income (loss) before income taxes from continuing operations	(7,496)		(1,810)		(5,246)		(7,340)		(4,568)		(2,573)		(1,101)		5,814		(21,892)		(2,428)		17,190
Other Income Tax Expense (Benefit), Continuing Operations	(5,072)		(751)		(2,627)		(3,812)		(712)		(1,437)		400		2,155		(12,262)		406		12,134
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
Less net income attributable to noncontrolling 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
Earnings Per Share, Diluted	(0.23)		(0.05)		0.39		(0.29)		0		0		0		0		(0.09)		0.14		$ 0.62
Basic net income (loss) per share attributable to Oppenheimer Holdings Inc.
Dividends per share	0.11		0.11		0.11		0.11		0.11		0.11		0.11		0.11		0.44		0.44
Market price of Class A Stock
High	19.65	[1]	16.49	[1]	16.66	[1]	16.98	[1]	20.98	[2]	26.8	[2]	27.99	[2]	24.41	[2]	19.65	[1]	27.99	[2]
Low	$ 13.65	[1]	$ 13.74	[1]	$ 13.63	[1]	$ 13.58	[1]	$ 15.6	[2]	$ 17.4	[2]	$ 22.3	[2]	$ 19.04	[2]	$ 13.58	[1]	$ 15.6	[2]

[1] The price quotations above were obtained from the New York Stock Exchange website.

[2] The price quotations above were obtained from the New York Stock Exchange website.