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				(4,357)
Share-based expense					1,317
Vested employee share plan awards					(6,060)
Adjustments to Additional Paid in Capital, Other					425
Net income (loss) attributable to Oppenheimer Holdings Inc.	$ (4,847)					(4,847)		$ (4,847)
Dividends paid ($0.11 per share)						(1,480)
Dividends received from non-controlling interest						6
Cumulative Effect on Retained Earnings, Net of Tax						(314)
Currency translation adjustment	1,424	[1]					1,424
Less net income attributable to non-controlling interest, net of tax	96							0	96
Dividends paid to non-controlling interest	816							0	(816)
Dividends paid to parent									(6)
Balance at end of period at Mar. 31, 2017	502,579		58,861		37,447	403,623	743	500,674	1,905
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				37
Repurchase of Class A non-voting common stock for cancellation				$ 0
Share-based expense					1,509
Vested employee share plan awards					(59)
Adjustments to Additional Paid in Capital, Other					0
Net income (loss) attributable to Oppenheimer Holdings Inc.	6,705					6,705		6,705
Dividends paid ($0.11 per share)						(1,456)
Dividends received from non-controlling interest						0
Cumulative Effect on Retained Earnings, Net of Tax						0
Currency translation adjustment	(142)	[1]					(142)
Less net income attributable to non-controlling interest, net of tax	4							0	4
Dividends paid to non-controlling interest	0								0
Dividends paid to parent									0
Balance at end of period at Mar. 31, 2018	$ 530,509		$ 58,529		$ 37,996	$ 432,179	$ 1,440	$ 530,144	$ 365

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