Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total		Share Capital	Share Capital Class A Stock	Contributed Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Parent	Non-Controlling Interest
Balance at beginning of period at Dec. 31, 2016			$ 59,361		$ 41,765	$ 410,258	$ (681)		$ 2,631
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A non-voting common stock				$ 3,857
Repurchase of Class A non-voting common stock for cancellation				(5,159)
Share-based expense					2,644
Vested employee share plan awards					(6,060)
Adjustments to Additional Paid in Capital, Other					425
Net income (loss) attributable to Oppenheimer Holdings Inc.	$ (6,166)					(6,166)		$ (6,166)
Dividends paid ($0.22 per share)						(2,940)
Dividends received from non-controlling interest						6
Cumulative Effect on Retained Earnings, Net of Tax						(314)
Currency translation adjustment	2,204	[1]					2,204
Less net income (loss) attributable to non-controlling interest, net of tax	105							0	105
Dividends paid to non-controlling interest	816							0	(816)
Dividends paid to parent									(6)
Balance at end of period at Jun. 30, 2017	501,114		58,059		38,774	400,844	1,523	499,200	1,914
Balance at beginning of period at Dec. 31, 2017	523,911		58,492		36,546	426,930	1,582	523,550	361
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A non-voting common stock				333
Repurchase of Class A non-voting common stock for cancellation				$ 0
Share-based expense					3,096
Vested employee share plan awards					(355)
Adjustments to Additional Paid in Capital, Other					0
Net income (loss) attributable to Oppenheimer Holdings Inc.	15,560					15,560		15,560
Dividends paid ($0.22 per share)						(2,913)
Dividends received from non-controlling interest						0
Cumulative Effect on Retained Earnings, Net of Tax						0
Currency translation adjustment	(979)	[1]					(979)
Less net income (loss) attributable to non-controlling interest, net of tax	(12)							0	(12)
Dividends paid to non-controlling interest	0								0
Dividends paid to parent									0
Balance at end of period at Jun. 30, 2018	$ 538,641		$ 58,825		$ 39,287	$ 439,577	$ 603	$ 538,292	$ 349

[1] No other comprehensive income (loss) is attributable to non-controlling interests.