Supplemental Guarantor Condensed Consolidated Financial Statements - Condensed Consolidating Balance Sheet (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
ASSETS
Cash and cash equivalents	$ 63,807	$ 98,294	$ 135,366	$ 70,329
Cash and securities segregated for regulatory and other purposes	18,594	36,323
Deposits with clearing organizations	36,510	23,679
Receivable from brokers, dealers and clearing organizations	314,475	364,873
Receivable from customers, net of allowance for credit losses of $2,427 ($2,423 in 2013)	864,189	868,869
Income tax receivable	4,240	6,562
Securities purchased under agreements to resell	251,606	184,825
Securities owned, including amounts pledged of $518,123 ($586,625 in 2013) at fair value	843,155	856,088
Notes receivable, net of accumulated amortization and allowance for uncollectibles of $42,211 and $8,606, respectively ($54,465 and $9,718, respectively, in 2013)	34,932	40,751
Office facilities, net of accumulated depreciation of $104,065 ($97,118 in 2013)	29,589	32,939
Loans held for sale	19,243	75,989
Mortgage servicing rights	30,140	28,879	26,983
Subordinated loan receivable	0	0
Intangible assets	31,700	31,700
Goodwill	137,889	137,889
Other assets	107,386	165,060
Deferred tax assets	0	0
Investment in subsidiaries	0	0
Intercompany receivables	0	0
Total assets	2,787,455	2,952,720
Liabilities
Drafts payable	35,373	48,198
Bank call loans	59,400	118,200
Payable to brokers, dealers and clearing organizations	257,161	223,315
Payable to customers	652,256	626,564
Securities sold under agreements to repurchase	687,440	757,491
Securities sold, but not yet purchased, at fair value	92,510	76,314
Accrued compensation	165,134	180,119
Accounts payable and other liabilities	141,352	192,552
Income tax payable	0	0
Senior secured notes	150,000	195,000
Subordinated indebtedness	0	0
Deferred tax liabilities, net of deferred tax assets of $65,502 ($65,122 in 2013)	13,097	7,096
Intercompany payables	0	0
Total liabilities	2,253,723	2,424,849
Stockholders’ equity
Stockholders’ equity attributable to Oppenheimer Holdings Inc.	527,644	522,518
Non-controlling interest	6,088	5,353
Total stockholders’ equity	533,732	527,871	505,001
Total liabilities and stockholders’ equity	2,787,455	2,952,720
Allowance for credit losses	2,427	2,423
Amounts pledged	518,123	586,625
Notes Receivable, Net Accumulated Amortization	42,211	54,465
Notes Receivable, Net Allowance for Uncollectibles	8,606	9,718
Net accumulated depreciation	103,547	97,118
Eliminations
ASSETS
Cash and cash equivalents	0	0	0	0
Cash and securities segregated for regulatory and other purposes	0	0
Deposits with clearing organizations	0	0
Receivable from brokers, dealers and clearing organizations	0	0
Receivable from customers, net of allowance for credit losses of $2,427 ($2,423 in 2013)	0	0
Income tax receivable	(51,134)	(40,521)
Securities purchased under agreements to resell	0	0
Securities owned, including amounts pledged of $518,123 ($586,625 in 2013) at fair value	0	0
Notes receivable, net of accumulated amortization and allowance for uncollectibles of $42,211 and $8,606, respectively ($54,465 and $9,718, respectively, in 2013)	0	0
Office facilities, net of accumulated depreciation of $104,065 ($97,118 in 2013)	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	(28,300)	(30,483)
Investment in subsidiaries	(1,109,833)	(1,109,003)
Intercompany receivables	(87,442)	(153,528)
Total assets	(1,389,267)	(1,446,093)
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	(88)
Income tax payable	(51,134)	(40,521)
Senior secured notes	0	0
Subordinated indebtedness	(112,558)	(112,558)
Deferred tax liabilities, net of deferred tax assets of $65,502 ($65,122 in 2013)	(28,300)	(30,483)
Intercompany payables	(87,442)	(153,528)
Total liabilities	(279,434)	(337,178)
Stockholders’ equity
Stockholders’ equity attributable to Oppenheimer Holdings Inc.	(1,109,833)	(1,108,915)
Non-controlling interest	0	0
Total stockholders’ equity	(1,109,833)	(1,108,915)
Total liabilities and stockholders’ equity	(1,389,267)	(1,446,093)
Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	1,557	30,901	40,658	11,882
Cash and securities segregated for regulatory and other purposes	0	0
Deposits with clearing organizations	0	0
Receivable from brokers, dealers and clearing organizations	0	0
Receivable from customers, net of allowance for credit losses of $2,427 ($2,423 in 2013)	0	0
Income tax receivable	27,304	27,589
Securities purchased under agreements to resell	0	0
Securities owned, including amounts pledged of $518,123 ($586,625 in 2013) at fair value	5,806	2,225
Notes receivable, net of accumulated amortization and allowance for uncollectibles of $42,211 and $8,606, respectively ($54,465 and $9,718, respectively, in 2013)	0	0
Office facilities, net of accumulated depreciation of $104,065 ($97,118 in 2013)	20,181	21,250
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	3,803	27,113
Deferred tax assets	309	309
Investment in subsidiaries	544,576	562,248
Intercompany receivables	0	0
Total assets	716,094	784,193
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	35,800	59,289
Income tax payable	22,189	22,189
Senior secured notes	0	0
Subordinated indebtedness	0	0
Deferred tax liabilities, net of deferred tax assets of $65,502 ($65,122 in 2013)	88	0
Intercompany payables	76,492	133,421
Total liabilities	134,569	214,899
Stockholders’ equity
Stockholders’ equity attributable to Oppenheimer Holdings Inc.	581,525	569,294
Non-controlling interest	0	0
Total stockholders’ equity	581,525	569,294
Total liabilities and stockholders’ equity	716,094	784,193
Non-Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	61,811	66,945	94,673	55,892
Cash and securities segregated for regulatory and other purposes	18,594	36,323
Deposits with clearing organizations	36,510	23,679
Receivable from brokers, dealers and clearing organizations	314,475	364,873
Receivable from customers, net of allowance for credit losses of $2,427 ($2,423 in 2013)	864,189	868,869
Income tax receivable	0	0
Securities purchased under agreements to resell	251,606	184,825
Securities owned, including amounts pledged of $518,123 ($586,625 in 2013) at fair value	837,349	853,863
Notes receivable, net of accumulated amortization and allowance for uncollectibles of $42,211 and $8,606, respectively ($54,465 and $9,718, respectively, in 2013)	34,932	40,751
Office facilities, net of accumulated depreciation of $104,065 ($97,118 in 2013)	9,408	11,689
Loans held for sale	19,243	75,989
Mortgage servicing rights	30,140	28,879
Subordinated loan receivable	0	0
Intangible assets	31,700	31,700
Goodwill	137,889	137,889
Other assets	101,897	135,150
Deferred tax assets	27,973	29,496
Investment in subsidiaries	0	0
Intercompany receivables	0	0
Total assets	2,777,716	2,890,920
Liabilities
Drafts payable	35,373	48,198
Bank call loans	59,400	118,200
Payable to brokers, dealers and clearing organizations	257,161	223,315
Payable to customers	652,256	626,564
Securities sold under agreements to repurchase	687,440	757,491
Securities sold, but not yet purchased, at fair value	92,510	76,314
Accrued compensation	165,134	180,119
Accounts payable and other liabilities	102,724	129,609
Income tax payable	26,505	15,892
Senior secured notes	0	0
Subordinated indebtedness	112,558	112,558
Deferred tax liabilities, net of deferred tax assets of $65,502 ($65,122 in 2013)	41,309	37,579
Intercompany payables	10,950	20,107
Total liabilities	2,243,320	2,345,946
Stockholders’ equity
Stockholders’ equity attributable to Oppenheimer Holdings Inc.	528,308	539,621
Non-controlling interest	6,088	5,353
Total stockholders’ equity	534,396	544,974
Total liabilities and stockholders’ equity	2,777,716	2,890,920
Parent
ASSETS
Cash and cash equivalents	439	448	35	2,555
Cash and securities segregated for regulatory and other purposes	0	0
Deposits with clearing organizations	0	0
Receivable from brokers, dealers and clearing organizations	0	0
Receivable from customers, net of allowance for credit losses of $2,427 ($2,423 in 2013)	0	0
Income tax receivable	28,070	19,494
Securities purchased under agreements to resell	0	0
Securities owned, including amounts pledged of $518,123 ($586,625 in 2013) at fair value	0	0
Notes receivable, net of accumulated amortization and allowance for uncollectibles of $42,211 and $8,606, respectively ($54,465 and $9,718, respectively, in 2013)	0	0
Office facilities, net of accumulated depreciation of $104,065 ($97,118 in 2013)	0	0
Loans held for sale	0	0
Mortgage servicing rights	0	0
Subordinated loan receivable		0
Intangible assets	0	0
Goodwill	0	0
Other assets	1,686	2,797
Deferred tax assets	18	678
Investment in subsidiaries	565,257	546,755
Intercompany receivables	87,442	153,528
Total assets	682,912	723,700
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	2,828	3,742
Income tax payable	2,440	2,440
Senior secured notes	150,000	195,000
Subordinated indebtedness		0
Deferred tax liabilities, net of deferred tax assets of $65,502 ($65,122 in 2013)	0	0
Intercompany payables	0	0
Total liabilities	155,268	201,182
Stockholders’ equity
Stockholders’ equity attributable to Oppenheimer Holdings Inc.	527,644	522,518
Non-controlling interest	0	0
Total stockholders’ equity	527,644	522,518	500,740
Total liabilities and stockholders’ equity	$ 682,912	$ 723,700