Supplemental Guarantor Condensed Consolidated Financial Statements - Condensed Consolidating Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
ASSETS
Cash and cash equivalents	$ 64,913	$ 63,364	$ 63,807	$ 98,294
Deposits with clearing organizations	38,185	49,490
Receivable from brokers, dealers and clearing organizations	214,934	365,791
Receivable from customers, net of allowance for credit losses of $794 ($2,545 in 2015)	847,386	840,355
Income tax receivable	5,816	12,231
Securities purchased under agreements to resell, at fair value	24,006	206,499
Securities owned, at fair value	707,108	734,831
Notes receivable, net of accumulated amortization and allowance for uncollectibles of $24,826 and $6,784, respectively ($54,919 and $8,444, respectively, in 2015)	30,099	32,849
Office facilities, net of accumulated depreciation of $104,065 ($97,118 in 2013)	27,233	28,285
Assets held for sale	5,188	99,881
Subordinated loan receivable	0	0
Intangible assets	31,700	31,700
Goodwill	137,889	137,889
Other assets	102,473	94,839
Deferred tax assets	0	0
Investment in subsidiaries	0	0
Intercompany receivables	0	0
Total assets	2,236,930	2,698,004
Liabilities
Drafts payable	39,228	48,011
Bank call loans	145,800	100,200
Payable to brokers, dealers and clearing organizations	221,389	164,546
Payable to customers	449,946	594,833
Securities sold under agreements to repurchase	378,084	651,445
Securities sold but not yet purchased, at fair value	85,050	126,493
Liabilities held for sale	1,217	74,680
Accrued compensation	145,053	149,092
Accounts payable and other liabilities	95,340	108,637
Income tax payable	0	0
Senior secured notes, net of debt issuance costs of $648 ($1,132 in 2015)	149,352	148,868
Subordinated indebtedness	0	0
Deferred tax liabilities, net	13,137	6,117
Intercompany payables	0	0
Total liabilities	1,723,596	2,172,922
Stockholders' equity
Stockholders' equity attributable to Oppenheimer Holdings Inc.	510,703	518,058
Noncontrolling interest	2,631	7,024
Total stockholders' equity	513,334	525,082	533,732
Total liabilities and stockholders' equity	2,236,930	2,698,004
Allowance for credit losses	794	2,545
Amounts pledged	438,385	546,334
Notes Receivable, Net Accumulated Amortization	24,826	54,919
Notes Receivable, Net Allowance for Uncollectibles	6,784	8,444
Net accumulated depreciation	84,073	104,812
Unamortized debt issuance expense	648	1,132
Eliminations
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 for credit losses of $794 ($2,545 in 2015)	0	0
Income tax receivable	(64,469)	(49,106)
Securities purchased under agreements to resell, at fair value	0	0
Securities owned, at fair value	0	0
Notes receivable, net of accumulated amortization and allowance for uncollectibles of $24,826 and $6,784, respectively ($54,919 and $8,444, respectively, in 2015)	0	0
Office facilities, net of accumulated depreciation of $104,065 ($97,118 in 2013)	0	0
Assets held for sale	0	0
Subordinated loan receivable	(112,558)	(112,558)
Intangible assets	0	0
Goodwill	0	0
Other assets	0	0
Deferred tax assets	(38,664)	(41,103)
Investment in subsidiaries	(1,068,390)	(1,109,971)
Intercompany receivables	(75,820)	(73,372)
Total assets	(1,359,901)	(1,386,110)
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
Liabilities held for sale	0	0
Accrued compensation	0	0
Accounts payable and other liabilities	0	0
Income tax payable	(64,469)	(49,106)
Senior secured notes, net of debt issuance costs of $648 ($1,132 in 2015)	0	0
Subordinated indebtedness	(112,558)	(112,558)
Deferred tax liabilities, net	(38,664)	(41,103)
Intercompany payables	(75,820)	(73,372)
Total liabilities	(291,511)	(276,139)
Stockholders' equity
Stockholders' equity attributable to Oppenheimer Holdings Inc.	(1,068,390)	(1,109,971)
Noncontrolling interest	0	0
Total stockholders' equity	(1,068,390)	(1,109,971)
Total liabilities and stockholders' equity	(1,359,901)	(1,386,110)
Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	10,284	2,586	1,557	30,901
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 $794 ($2,545 in 2015)	0	0
Income tax receivable	28,289	27,536
Securities purchased under agreements to resell, at fair value	0	0
Securities owned, at fair value	23,227	1,183
Notes receivable, net of accumulated amortization and allowance for uncollectibles of $24,826 and $6,784, respectively ($54,919 and $8,444, respectively, in 2015)	0	0
Office facilities, net of accumulated depreciation of $104,065 ($97,118 in 2013)	21,963	20,793
Assets held for sale	0	0
Subordinated loan receivable	112,558	112,558
Intangible assets	0	0
Goodwill	0	0
Other assets	2,598	3,224
Deferred tax assets	309	330
Investment in subsidiaries	483,623	532,651
Intercompany receivables	37,914	13,185
Total assets	720,765	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
Liabilities held for sale	0	0
Accrued compensation	0	0
Accounts payable and other liabilities	34,920	35,812
Income tax payable	22,189	22,189
Senior secured notes, net of debt issuance costs of $648 ($1,132 in 2015)	0	0
Subordinated indebtedness	0	0
Deferred tax liabilities, net	7	0
Intercompany payables	62,205	62,204
Total liabilities	119,321	120,205
Stockholders' equity
Stockholders' equity attributable to Oppenheimer Holdings Inc.	601,444	593,841
Noncontrolling interest	0	0
Total stockholders' equity	601,444	593,841
Total liabilities and stockholders' equity	720,765	714,046
Non-Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	54,400	59,871	61,811	66,945
Deposits with clearing organizations	38,185	49,490
Receivable from brokers, dealers and clearing organizations	214,934	365,791
Receivable from customers, net of allowance for credit losses of $794 ($2,545 in 2015)	847,386	840,355
Income tax receivable	0	0
Securities purchased under agreements to resell, at fair value	24,006	206,499
Securities owned, at fair value	683,881	733,648
Notes receivable, net of accumulated amortization and allowance for uncollectibles of $24,826 and $6,784, respectively ($54,919 and $8,444, respectively, in 2015)	30,099	32,849
Office facilities, net of accumulated depreciation of $104,065 ($97,118 in 2013)	5,270	7,492
Assets held for sale	5,188	99,881
Subordinated loan receivable	0	0
Intangible assets	31,700	31,700
Goodwill	137,889	137,889
Other assets	99,804	91,546
Deferred tax assets	37,961	40,456
Investment in subsidiaries	0	0
Intercompany receivables	0	0
Total assets	2,210,703	2,697,467
Liabilities
Drafts payable	39,228	48,011
Bank call loans	145,800	100,200
Payable to brokers, dealers and clearing organizations	221,389	164,546
Payable to customers	449,946	594,833
Securities sold under agreements to repurchase	378,084	651,445
Securities sold but not yet purchased, at fair value	85,050	126,493
Liabilities held for sale	1,217	74,680
Accrued compensation	145,053	149,092
Accounts payable and other liabilities	57,552	69,590
Income tax payable	39,840	24,477
Senior secured notes, net of debt issuance costs of $648 ($1,132 in 2015)	0	0
Subordinated indebtedness	112,558	112,558
Deferred tax liabilities, net	51,794	47,220
Intercompany payables	13,615	11,168
Total liabilities	1,741,126	2,174,313
Stockholders' equity
Stockholders' equity attributable to Oppenheimer Holdings Inc.	466,946	516,130
Noncontrolling interest	2,631	7,024
Total stockholders' equity	469,577	523,154
Total liabilities and stockholders' equity	2,210,703	2,697,467
Parent
ASSETS
Cash and cash equivalents	229	907	439	$ 448
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 $794 ($2,545 in 2015)	0	0
Income tax receivable	41,996	33,801
Securities purchased under agreements to resell, at fair value	0	0
Securities owned, at fair value	0	0
Notes receivable, net of accumulated amortization and allowance for uncollectibles of $24,826 and $6,784, respectively ($54,919 and $8,444, respectively, in 2015)	0	0
Office facilities, net of accumulated depreciation of $104,065 ($97,118 in 2013)	0	0
Assets held for sale	0	0
Subordinated loan receivable	0	0
Intangible assets	0	0
Goodwill	0	0
Other assets	71	69
Deferred tax assets	394	317
Investment in subsidiaries	584,767	577,320
Intercompany receivables	37,906	60,187
Total assets	665,363	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
Liabilities held for sale	0	0
Accrued compensation	0	0
Accounts payable and other liabilities	2,868	3,235
Income tax payable	2,440	2,440
Senior secured notes, net of debt issuance costs of $648 ($1,132 in 2015)	149,352	148,868
Subordinated indebtedness	0	0
Deferred tax liabilities, net	0	0
Intercompany payables	0	0
Total liabilities	154,660	154,543
Stockholders' equity
Stockholders' equity attributable to Oppenheimer Holdings Inc.	510,703	518,058
Noncontrolling interest	0	0
Total stockholders' equity	510,703	518,058	$ 527,644
Total liabilities and stockholders' equity	$ 665,363	$ 672,601