Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	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, 2015			$ 57,520		$ 44,438	$ 417,001	$ (901)		$ 7,024
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A non-voting common stock	$ 5,776			$ 5,776
Repurchase of Class A non-voting common stock for cancellation				(3,935)
Tax deficiency from share-based awards					(740)
Share-based expense					5,184
Vested employee share plan awards					(7,117)
Net income (loss) attributable to Oppenheimer Holdings Inc.	(1,161)					(1,161)		$ (1,161)
Dividends paid ($0.44 per share for the years 2012, 2013 & 2014)						(5,887)
Dividends received from non-controlling interest						305
Currency translation adjustment	220	[1]					220
Less net income (loss) attributable to non-controlling interest, net of tax	1,652							0	1,652
Dividends paid to non-controlling interest	5,740								(5,740)
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Subsidiaries and Equity Method Investees									(305)
Balance at end of year at Dec. 31, 2016	513,334		59,361		41,765	410,258	(681)		2,631
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.								510,703
Non-controlling interest									2,631
Issuance of Class A non-voting common stock	6,569			6,595
Repurchase of Class A non-voting common stock for cancellation				(7,464)
Tax deficiency from share-based awards					0
Share-based expense					5,583
Vested employee share plan awards					(11,227)
Net income (loss) attributable to Oppenheimer Holdings Inc.	22,816					22,816		22,816
Dividends paid ($0.44 per share for the years 2012, 2013 & 2014)						(5,836)
Dividends received from non-controlling interest						6
Currency translation adjustment	2,263	[1]					2,263
Less net income (loss) attributable to non-controlling interest, net of tax	184							0	184
Dividends paid to non-controlling interest	2,448								(2,448)
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Subsidiaries and Equity Method Investees									(6)
Balance at end of year at Dec. 31, 2017	523,911		58,492		36,546	426,930	1,582	523,550	361
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments to Additional Paid in Capital, Other						(314)
Cumulative-effect adjustment from adoption of new accounting update of employee share-based accounting					425
Stockholders' equity attributable to Oppenheimer Holdings Inc.	523,550							523,550
Non-controlling interest	361							0	361
Issuance of Class A non-voting common stock	724			794
Repurchase of Class A non-voting common stock for cancellation				$ (5,894)
Tax deficiency from share-based awards					0
Share-based expense					6,061
Vested employee share plan awards					(831)
Net income (loss) attributable to Oppenheimer Holdings Inc.	28,892					28,892		28,892
Dividends paid ($0.44 per share for the years 2012, 2013 & 2014)						(5,833)
Dividends received from non-controlling interest						0
Currency translation adjustment	(1,417)	[1]					(1,417)
Less net income (loss) attributable to non-controlling interest, net of tax	(16)							0	(16)
Dividends paid to non-controlling interest	372							0	(345)
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Subsidiaries and Equity Method Investees									0
Balance at end of year at Dec. 31, 2018	545,322		$ 53,392		41,776	449,989	$ 165	545,322
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.	545,322							$ 545,322
Non-controlling interest	$ 0								$ 0

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