Consolidated Statements of Changes in Stockholders' Equity - USD ($)	Total		Share Capital	Share Capital Common Class A [Member]	Contributed Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Parent	Non-Controlling Interest
Balance at beginning of year at Dec. 31, 2014			$ 62,397,000		$ 45,118,000	$ 421,047,000	$ (918,000)		$ 6,088,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A non-voting common stock	$ 3,373,000			$ 3,373,000
Repurchase of Class A non-voting common stock for cancellation				(8,250,000)
Tax deficiency from share-based awards					(277,000)
Share-based expense					4,653,000
Vested employee share plan awards					(5,056,000)
Net income (loss) attributable to Oppenheimer Holdings Inc.	1,962,000					1,962,000		$ 1,962,000
Dividends paid ($0.44 per share for the years 2012, 2013 & 2014)						(6,008,000)
Dividends received from noncontrolling interest						0
Currency translation adjustment	17,000	[1]					17,000
Less net income attributable to noncontrolling interest, net of tax	936,000							0	936,000
Dividends paid to noncontrolling interest	0								0
Cash Dividends Paid to Parent Company									0
Balance at end of year at Dec. 31, 2015	525,082,000		57,520,000		44,438,000	417,001,000	(901,000)		7,024,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment from adoption of new accounting update of employee share-based accounting					0
Stockholders' equity attributable to Oppenheimer Holdings Inc.								518,058,000
Noncontrolling interest									7,024,000
Issuance of Class A non-voting common stock	5,776,000			5,776,000
Repurchase of Class A non-voting common stock for cancellation				(3,935,000)
Tax deficiency from share-based awards					(740,000)
Share-based expense					5,184,000
Vested employee share plan awards					(7,117,000)
Net income (loss) attributable to Oppenheimer Holdings Inc.	(1,161,000)					(1,161,000)		(1,161,000)
Dividends paid ($0.44 per share for the years 2012, 2013 & 2014)						(5,887,000)
Dividends received from noncontrolling interest						305,000
Currency translation adjustment	220,000	[1]					220,000
Less net income attributable to noncontrolling interest, net of tax	1,652,000							0	1,652,000
Dividends paid to noncontrolling interest	5,740,000								(5,740,000)
Cash Dividends Paid to Parent Company									(305,000)
Balance at end of year at Dec. 31, 2016	513,334,000		59,361,000		41,765,000	410,258,000	(681,000)	510,703,000	2,631,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments to Additional Paid in Capital, Other						0
Cumulative-effect adjustment from adoption of new accounting update of employee share-based accounting					0
Stockholders' equity attributable to Oppenheimer Holdings Inc.	510,703,000							510,703,000
Noncontrolling interest	2,631,000							0	2,631,000
Issuance of Class A non-voting common stock	6,569,000			6,595,000
Repurchase of Class A non-voting common stock for cancellation				$ (7,464,000)
Tax deficiency from share-based awards					0
Share-based expense					5,583,000
Vested employee share plan awards					(11,227,000)
Net income (loss) attributable to Oppenheimer Holdings Inc.	22,816,000					22,816,000		22,816,000
Dividends paid ($0.44 per share for the years 2012, 2013 & 2014)						(5,836,000)
Dividends received from noncontrolling interest						6,000
Currency translation adjustment	2,263,000	[1]					2,263,000
Less net income attributable to noncontrolling interest, net of tax	184,000							0	184,000
Dividends paid to noncontrolling interest	2,448,000							0	(2,448,000)
Cash Dividends Paid to Parent Company									(6,000)
Balance at end of year at Dec. 31, 2017	523,911,000		$ 58,492,000		36,546,000	426,930,000	$ 1,582,000	523,550,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments to Additional Paid in Capital, Other						$ (314,000)
Cumulative-effect adjustment from adoption of new accounting update of employee share-based accounting					$ 425,000
Stockholders' equity attributable to Oppenheimer Holdings Inc.	523,550,000							523,550,000
Noncontrolling interest	$ 361,000							$ 0	$ 361,000

[1] No other comprehensive income is attributable to noncontrolling interests.