Supplemental Guarantor Condensed Consolidated Financial Statements - Condensed Consolidating Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
ASSETS
Cash and cash equivalents	$ 62,421	$ 64,913	$ 62,479	$ 63,364
Deposits with clearing organizations	41,902	38,185
Receivable from brokers, dealers and clearing organizations	232,682	214,934
Receivable from customers, net of allowance for credit losses of $761 ($794 in 2016)	830,084	847,386
Income tax receivable	9,119	5,816
Securities purchased under agreements to resell, at fair value	3,896	24,006
Securities owned, at fair value	1,002,705	707,108
Notes receivable, net of accumulated amortization and allowance for uncollectibles of $23,866 and $7,300, respectively ($24,826 and $6,784, respectively, in 2016)	33,808	30,099
Office facilities, net of accumulated depreciation of $104,065 ($97,118 in 2013)	27,351	27,233
Assets held for sale	1,330	5,188
Subordinated loan receivable	0	0
Intangible assets	31,700	31,700
Goodwill	137,889	137,889
Other assets	110,540	102,473
Deferred tax assets	0	0
Investment in subsidiaries	0	0
Intercompany receivables	0	0
Total assets	2,525,427	2,236,930
Liabilities
Drafts payable	32,783	39,228
Bank call loans	195,700	145,800
Payable to brokers, dealers and clearing organizations	175,204	221,389
Payable to customers	504,348	449,946
Securities sold under agreements to repurchase	456,090	378,084
Securities sold but not yet purchased, at fair value	299,472	85,050
Liabilities held for sale	1,421	1,217
Accrued compensation	95,164	145,053
Accounts payable and other liabilities	99,249	95,340
Income tax payable	0	0
Senior secured notes, net of debt issuance costs of $527 ($648 in 2016)	149,473	149,352
Subordinated indebtedness	0	0
Deferred tax liabilities, net	13,944	13,137
Intercompany payables	0	0
Total liabilities	2,022,848	1,723,596
Stockholders' equity
Stockholders' equity attributable to Oppenheimer Holdings Inc.	500,674	510,703
Noncontrolling interest	1,905	2,631
Total stockholders' equity	502,579	513,334	516,346
Total liabilities and stockholders' equity	2,525,427	2,236,930
Allowance for credit losses	761	794
Amounts pledged	705,988	438,385
Notes Receivable, Net Accumulated Amortization	23,866	24,826
Notes Receivable, Net Allowance for Uncollectibles	7,300	6,784
Net accumulated depreciation	85,672	84,073
Unamortized debt issuance expense	527	648
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 $761 ($794 in 2016)	0	0
Income tax receivable	(62,416)	(64,469)
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 $23,866 and $7,300, respectively ($24,826 and $6,784, respectively, in 2016)	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	(34,946)	(38,664)
Investment in subsidiaries	(1,057,416)	(1,068,390)
Intercompany receivables	(73,826)	(75,820)
Total assets	(1,341,162)	(1,359,901)
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	(62,416)	(64,469)
Senior secured notes, net of debt issuance costs of $527 ($648 in 2016)	0	0
Subordinated indebtedness	(112,558)	(112,558)
Deferred tax liabilities, net	(34,946)	(38,664)
Intercompany payables	(73,826)	(75,820)
Total liabilities	(283,746)	(291,511)
Stockholders' equity
Stockholders' equity attributable to Oppenheimer Holdings Inc.	(1,057,416)	(1,068,390)
Noncontrolling interest	0	0
Total stockholders' equity	(1,057,416)	(1,068,390)
Total liabilities and stockholders' equity	(1,341,162)	(1,359,901)
Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	14,384	10,284	119	2,586
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 $761 ($794 in 2016)	0	0
Income tax receivable	28,284	28,289
Securities purchased under agreements to resell, at fair value	0	0
Securities owned, at fair value	23,742	23,227
Notes receivable, net of accumulated amortization and allowance for uncollectibles of $23,866 and $7,300, respectively ($24,826 and $6,784, respectively, in 2016)	0	0
Office facilities, net of accumulated depreciation of $104,065 ($97,118 in 2013)	21,489	21,963
Assets held for sale	0	0
Subordinated loan receivable	112,558	112,558
Intangible assets	0	0
Goodwill	0	0
Other assets	927	2,598
Deferred tax assets	0	309
Investment in subsidiaries	473,618	483,623
Intercompany receivables	43,750	37,914
Total assets	718,752	720,765
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	34,248	34,920
Income tax payable	22,189	22,189
Senior secured notes, net of debt issuance costs of $527 ($648 in 2016)	0	0
Subordinated indebtedness	0	0
Deferred tax liabilities, net	22	7
Intercompany payables	62,163	62,205
Total liabilities	118,622	119,321
Stockholders' equity
Stockholders' equity attributable to Oppenheimer Holdings Inc.	600,130	601,444
Noncontrolling interest	0	0
Total stockholders' equity	600,130	601,444
Total liabilities and stockholders' equity	718,752	720,765
Non-Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	47,131	54,400	62,164	59,871
Deposits with clearing organizations	41,902	38,185
Receivable from brokers, dealers and clearing organizations	232,682	214,934
Receivable from customers, net of allowance for credit losses of $761 ($794 in 2016)	830,084	847,386
Income tax receivable	0	0
Securities purchased under agreements to resell, at fair value	3,896	24,006
Securities owned, at fair value	978,963	683,881
Notes receivable, net of accumulated amortization and allowance for uncollectibles of $23,866 and $7,300, respectively ($24,826 and $6,784, respectively, in 2016)	33,808	30,099
Office facilities, net of accumulated depreciation of $104,065 ($97,118 in 2013)	5,862	5,270
Assets held for sale	1,330	5,188
Subordinated loan receivable	0	0
Intangible assets	31,700	31,700
Goodwill	137,889	137,889
Other assets	109,530	99,804
Deferred tax assets	34,280	37,961
Investment in subsidiaries	0	0
Intercompany receivables	0	0
Total assets	2,489,057	2,210,703
Liabilities
Drafts payable	32,783	39,228
Bank call loans	195,700	145,800
Payable to brokers, dealers and clearing organizations	175,204	221,389
Payable to customers	504,348	449,946
Securities sold under agreements to repurchase	456,090	378,084
Securities sold but not yet purchased, at fair value	299,472	85,050
Liabilities held for sale	1,421	1,217
Accrued compensation	95,164	145,053
Accounts payable and other liabilities	58,808	57,552
Income tax payable	37,787	39,840
Senior secured notes, net of debt issuance costs of $527 ($648 in 2016)	0	0
Subordinated indebtedness	112,558	112,558
Deferred tax liabilities, net	48,868	51,794
Intercompany payables	11,663	13,615
Total liabilities	2,029,866	1,741,126
Stockholders' equity
Stockholders' equity attributable to Oppenheimer Holdings Inc.	457,286	466,946
Noncontrolling interest	1,905	2,631
Total stockholders' equity	459,191	469,577
Total liabilities and stockholders' equity	2,489,057	2,210,703
Parent
ASSETS
Cash and cash equivalents	906	229	196	$ 907
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 $761 ($794 in 2016)	0	0
Income tax receivable	43,251	41,996
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 $23,866 and $7,300, respectively ($24,826 and $6,784, respectively, in 2016)	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	83	71
Deferred tax assets	666	394
Investment in subsidiaries	583,798	584,767
Intercompany receivables	30,076	37,906
Total assets	658,780	665,363
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	6,193	2,868
Income tax payable	2,440	2,440
Senior secured notes, net of debt issuance costs of $527 ($648 in 2016)	149,473	149,352
Subordinated indebtedness	0	0
Deferred tax liabilities, net	0	0
Intercompany payables	0	0
Total liabilities	158,106	154,660
Stockholders' equity
Stockholders' equity attributable to Oppenheimer Holdings Inc.	500,674	510,703
Noncontrolling interest	0	0
Total stockholders' equity	500,674	510,703	$ 509,384
Total liabilities and stockholders' equity	$ 658,780	$ 665,363