Condensed Consolidating Financial Information - Condensed Consolidating Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
ASSETS
Cash and cash equivalents	$ 62,479	$ 63,364	$ 66,918	$ 63,807
Deposits with clearing organizations	56,567	49,490
Receivable from brokers, dealers and clearing organizations	263,363	360,913
Receivable from customers, net of allowance	791,631	840,355
Income tax receivable	17,261	10,937
Securities purchased under agreements to resell	0	206,499
Securities owned	1,036,782	735,393
Notes receivable, net of accumulated amortization and allowance for uncollectibles	32,869	32,849
Office facilities, net of accumulated depreciation	28,518	28,290
Loans held for sale	13,532	60,234
Mortgage servicing rights	28,024	28,168	28,391	30,140
Subordinated loan receivable	0	0
Intangible assets	31,700	31,700
Goodwill	137,889	137,889
Other assets	120,249	105,751
Deferred tax assets	0	0
Investment in subsidiaries	0	0
Intercompany receivables	0	0
Total assets	2,620,864	2,691,832
Liabilities
Drafts payable	37,663	48,011
Bank call loans	148,300	100,200
Payable to brokers, dealers and clearing organizations	207,879	164,546
Payable to customers	521,557	594,833
Securities sold under agreements to repurchase	529,752	651,445
Securities sold, but not yet purchased, at fair value	270,952	126,493
Accrued compensation	93,835	150,898
Accounts payable and other liabilities	126,183	164,783
Income tax payable	0	0
Long-term Debt	148,989	148,868
Subordinated indebtedness	0	0
Deferred Tax Liabilities, Net	19,408	16,673
Intercompany payables	0	0
Total liabilities	2,104,518	2,166,750
Stockholders’ equity
Stockholders’ equity attributable to Oppenheimer Holdings Inc.	509,384	518,058
Noncontrolling interest	6,962	7,024
Total stockholders’ equity	516,346	525,082	536,669
Total liabilities and stockholders’ equity	2,620,864	2,691,832
Unamortized Debt Issuance Expense	1,011	1,132
Net accumulated depreciation	106,206	104,961
Accumulated amortization	58,350	54,919
Accumulated allowance	8,722	8,444
Allowance for credit losses	2,573	2,545
Amounts pledged	705,835	546,334
Eliminations [Member]
ASSETS
Cash and cash equivalents	0	0	0	0
Deposits with clearing organizations	0	0
Receivable from brokers, dealers and clearing organizations	0	0
Receivable from customers, net of allowance	0	0
Income tax receivable	(45,177)	(50,400)
Securities purchased under agreements to resell		0
Securities owned	0	0
Notes receivable, net of accumulated amortization and allowance for uncollectibles	0	0
Office facilities, net of accumulated depreciation	0	0
Loans held for sale	0	0
Mortgage servicing rights	0	0
Subordinated loan receivable	(112,558)	(112,558)
Intangible assets	0	0
Goodwill	0	0
Other assets	0	0
Deferred tax assets	(29,002)	(30,547)
Investment in subsidiaries	(1,105,359)	(1,109,971)
Intercompany receivables	(72,280)	(73,372)
Total assets	(1,364,376)	(1,376,848)
Liabilities
Drafts payable	0	0
Bank call loans	0	0
Payable to brokers, dealers and clearing organizations	0	0
Payable to customers	0	0
Securities sold under agreements to repurchase	0	0
Securities sold, but not yet purchased, at fair value	0	0
Accrued compensation	0	0
Accounts payable and other liabilities	0	0
Income tax payable	(45,177)	(50,400)
Long-term Debt	0	0
Subordinated indebtedness	(112,558)	(112,558)
Deferred Tax Liabilities, Net	(29,002)	(30,547)
Intercompany payables	(72,280)	(73,372)
Total liabilities	(259,017)	(266,877)
Stockholders’ equity
Stockholders’ equity attributable to Oppenheimer Holdings Inc.	(1,105,359)	(1,109,971)
Noncontrolling interest	0	0
Total stockholders’ equity	(1,105,359)	(1,109,971)
Total liabilities and stockholders’ equity	(1,364,376)	(1,376,848)
Parent Company [Member]
ASSETS
Cash and cash equivalents	196	907	1	439
Deposits with clearing organizations	0	0
Receivable from brokers, dealers and clearing organizations	0	0
Receivable from customers, net of allowance	0	0
Income tax receivable	34,696	33,801
Securities purchased under agreements to resell		0
Securities owned	0	0
Notes receivable, net of accumulated amortization and allowance for uncollectibles	0	0
Office facilities, net of accumulated depreciation	0	0
Loans held for sale	0	0
Mortgage servicing rights	0	0
Subordinated loan receivable	0	0
Intangible assets	0	0
Goodwill	0	0
Other assets	138	69
Deferred tax assets	1,135	317
Investment in subsidiaries	577,002	577,320
Intercompany receivables	53,871	60,187
Total assets	667,038	672,601
Liabilities
Drafts payable	0	0
Bank call loans	0	0
Payable to brokers, dealers and clearing organizations	0	0
Payable to customers	0	0
Securities sold under agreements to repurchase	0	0
Securities sold, but not yet purchased, at fair value	0	0
Accrued compensation	0	0
Accounts payable and other liabilities	6,225	3,235
Income tax payable	2,440	2,440
Long-term Debt	148,989	148,868
Subordinated indebtedness	0	0
Deferred Tax Liabilities, Net	0	0
Intercompany payables	0	0
Total liabilities	157,654	154,543
Stockholders’ equity
Stockholders’ equity attributable to Oppenheimer Holdings Inc.	509,384	518,058
Noncontrolling interest	0	0
Total stockholders’ equity	509,384	518,058
Total liabilities and stockholders’ equity	667,038	672,601
Guarantor Subsidiaries [Member]
ASSETS
Cash and cash equivalents	119	2,586	1,993	1,557
Deposits with clearing organizations	0	0
Receivable from brokers, dealers and clearing organizations	0	0
Receivable from customers, net of allowance	0	0
Income tax receivable	27,742	27,536
Securities purchased under agreements to resell		0
Securities owned	1,213	1,183
Notes receivable, net of accumulated amortization and allowance for uncollectibles	0	0
Office facilities, net of accumulated depreciation	21,477	20,793
Loans held for sale	0	0
Mortgage servicing rights	0	0
Subordinated loan receivable	112,558	112,558
Intangible assets	0	0
Goodwill	0	0
Other assets	2,739	3,224
Deferred tax assets	317	330
Investment in subsidiaries	528,357	532,651
Intercompany receivables	18,409	13,185
Total assets	712,931	714,046
Liabilities
Drafts payable	0	0
Bank call loans	0	0
Payable to brokers, dealers and clearing organizations	0	0
Payable to customers	0	0
Securities sold under agreements to repurchase	0	0
Securities sold, but not yet purchased, at fair value	0	0
Accrued compensation	0	0
Accounts payable and other liabilities	35,488	35,812
Income tax payable	22,189	22,189
Long-term Debt	0	0
Subordinated indebtedness	0	0
Deferred Tax Liabilities, Net	0	0
Intercompany payables	62,204	62,204
Total liabilities	119,881	120,205
Stockholders’ equity
Stockholders’ equity attributable to Oppenheimer Holdings Inc.	593,050	593,841
Noncontrolling interest	0	0
Total stockholders’ equity	593,050	593,841
Total liabilities and stockholders’ equity	712,931	714,046
Non-Guarantor Subsidiaries [Member]
ASSETS
Cash and cash equivalents	62,164	59,871	$ 64,924	$ 61,811
Deposits with clearing organizations	56,567	49,490
Receivable from brokers, dealers and clearing organizations	263,363	360,913
Receivable from customers, net of allowance	791,631	840,355
Income tax receivable	0	0
Securities purchased under agreements to resell		206,499
Securities owned	1,035,569	734,210
Notes receivable, net of accumulated amortization and allowance for uncollectibles	32,869	32,849
Office facilities, net of accumulated depreciation	7,041	7,497
Loans held for sale	13,532	60,234
Mortgage servicing rights	28,024	28,168
Subordinated loan receivable	0	0
Intangible assets	31,700	31,700
Goodwill	137,889	137,889
Other assets	117,372	102,458
Deferred tax assets	27,550	29,900
Investment in subsidiaries	0	0
Intercompany receivables	0	0
Total assets	2,605,271	2,682,033
Liabilities
Drafts payable	37,663	48,011
Bank call loans	148,300	100,200
Payable to brokers, dealers and clearing organizations	207,879	164,546
Payable to customers	521,557	594,833
Securities sold under agreements to repurchase	529,752	651,445
Securities sold, but not yet purchased, at fair value	270,952	126,493
Accrued compensation	93,835	150,898
Accounts payable and other liabilities	84,470	125,736
Income tax payable	20,548	25,771
Long-term Debt	0	0
Subordinated indebtedness	112,558	112,558
Deferred Tax Liabilities, Net	48,410	47,220
Intercompany payables	10,076	11,168
Total liabilities	2,086,000	2,158,879
Stockholders’ equity
Stockholders’ equity attributable to Oppenheimer Holdings Inc.	512,309	516,130
Noncontrolling interest	6,962	7,024
Total stockholders’ equity	519,271	523,154
Total liabilities and stockholders’ equity	$ 2,605,271	$ 2,682,033