Condensed Consolidating Financial Information - Condensed Consolidating Balance Sheet (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
ASSETS
Cash and cash equivalents	$ 65,174	$ 98,294	$ 106,098	$ 135,366
Cash and securities segregated for regulatory and other purposes	19,117	36,323
Deposits with clearing organizations	32,185	23,679
Receivable from brokers, dealers and clearing organizations	351,317	364,873
Receivable from customers, net of allowance for credit losses	951,015	868,869
Income tax receivable	13,240	6,562
Securities purchased under agreements to resell	250,000	184,825
Securities owned, including amounts pledged of $664,654 ($586,625 in 2013), at fair value	944,471	856,088
Notes receivable, net	37,816	40,751
Office facilities, net	31,262	32,939
Intangible assets	31,700	31,700
Goodwill	137,889	137,889
Loans held for sale	15,806	75,989
Mortgage servicing rights	29,115	28,879	27,665	26,983
Other assets	134,851	165,060
Total assets	3,044,958	2,952,720
Liabilities
Drafts payable	32,913	48,198
Bank call loans	147,200	118,200
Payable to brokers, dealers and clearing organizations	255,432	223,315
Payable to customers	684,884	626,564
Securities sold under agreements to repurchase	816,606	757,491
Securities sold, but not yet purchased, at fair value	126,092	76,314
Accrued compensation	122,210	180,119
Accounts payable and other liabilities	165,619	192,552
Senior secured notes	150,000	195,000
Deferred tax liabilities, net	14,395	7,096
Total liabilities	2,515,351	2,424,849
Stockholders’ equity
Stockholders' equity attributable to Oppenheimer Holdings Inc.	523,757	522,518
Non-controlling interest	5,850	5,353
Total stockholders' equity	529,607	527,871	511,766
Total liabilities and stockholders' equity	3,044,958	2,952,720
Eliminations [Member]
ASSETS
Income tax receivable	(38,268)	(39,704)
Subordinated loan receivable	(112,558)	(112,558)
Deferred tax assets, net	(24,465)	(30,483)
Investment in subsidiaries	(1,249,492)	(1,274,360)
Intercompany receivables	(62,701)	(64,501)
Total assets	(1,487,484)	(1,521,606)
Liabilities
Accounts payable and other liabilities		(88)
Income tax payable	(38,268)	(39,704)
Subordinated indebtedness	(112,558)	(112,558)
Deferred tax liabilities, net	(24,465)	(30,483)
Intercompany payables	(62,701)	(64,501)
Total liabilities	(237,992)	(247,334)
Stockholders’ equity
Stockholders' equity attributable to Oppenheimer Holdings Inc.	(1,249,492)	(1,274,272)
Total stockholders' equity	(1,249,492)	(1,274,272)
Total liabilities and stockholders' equity	(1,487,484)	(1,521,606)
Parent Company [Member]
ASSETS
Cash and cash equivalents	1,198	448	153	35
Income tax receivable	24,593	19,494
Deferred tax assets, net	213	678
Other assets	1,950	2,797
Investment in subsidiaries	556,732	546,755
Intercompany receivables	94,333	153,528
Total assets	679,019	723,700
Liabilities
Accounts payable and other liabilities	2,822	3,742
Income tax payable	2,440	2,440
Senior secured notes	150,000	195,000
Total liabilities	155,262	201,182
Stockholders’ equity
Stockholders' equity attributable to Oppenheimer Holdings Inc.	523,757	522,518
Total stockholders' equity	523,757	522,518
Total liabilities and stockholders' equity	679,019	723,700
Guarantor Subsidiaries [Member]
ASSETS
Cash and cash equivalents	6,560	30,901	36,184	40,658
Income tax receivable	27,611	27,589
Securities owned, including amounts pledged of $664,654 ($586,625 in 2013), at fair value	5,669	2,225
Subordinated loan receivable	112,558	112,558
Office facilities, net	20,529	21,250
Deferred tax assets, net	309	309
Other assets	27,034	27,113
Investment in subsidiaries	873,235	910,230
Intercompany receivables	(21,472)	(68,920)
Total assets	1,052,033	1,063,255
Liabilities
Accounts payable and other liabilities	58,483	59,289
Income tax payable	22,189	22,189
Deferred tax liabilities, net	60
Intercompany payables	62,701	64,501
Total liabilities	143,433	145,979
Stockholders’ equity
Stockholders' equity attributable to Oppenheimer Holdings Inc.	908,600	917,276
Total stockholders' equity	908,600	917,276
Total liabilities and stockholders' equity	1,052,033	1,063,255
Non-Guarantor Subsidiaries [Member]
ASSETS
Cash and cash equivalents	57,416	66,945	69,761	94,673
Cash and securities segregated for regulatory and other purposes	19,117	36,323
Deposits with clearing organizations	32,185	23,679
Receivable from brokers, dealers and clearing organizations	351,317	364,873
Receivable from customers, net of allowance for credit losses	951,015	868,869
Income tax receivable	(696)	(817)
Securities purchased under agreements to resell	250,000	184,825
Securities owned, including amounts pledged of $664,654 ($586,625 in 2013), at fair value	938,802	853,863
Notes receivable, net	37,816	40,751
Office facilities, net	10,733	11,689
Deferred tax assets, net	23,943	29,496
Intangible assets	31,700	31,700
Goodwill	137,889	137,889
Loans held for sale	15,806	75,989
Mortgage servicing rights	29,115	28,879
Other assets	105,867	135,150
Investment in subsidiaries	(180,475)	(182,625)
Intercompany receivables	(10,160)	(20,107)
Total assets	2,801,390	2,687,371
Liabilities
Drafts payable	32,913	48,198
Bank call loans	147,200	118,200
Payable to brokers, dealers and clearing organizations	255,432	223,315
Payable to customers	684,884	626,564
Securities sold under agreements to repurchase	816,606	757,491
Securities sold, but not yet purchased, at fair value	126,092	76,314
Accrued compensation	122,210	180,119
Accounts payable and other liabilities	104,314	129,609
Income tax payable	13,639	15,075
Subordinated indebtedness	112,558	112,558
Deferred tax liabilities, net	38,800	37,579
Total liabilities	2,454,648	2,325,022
Stockholders’ equity
Stockholders' equity attributable to Oppenheimer Holdings Inc.	340,892	356,996
Non-controlling interest	5,850	5,353
Total stockholders' equity	346,742	362,349
Total liabilities and stockholders' equity	$ 2,801,390	$ 2,687,371