Regulatory Requirements (Details)	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2021 EUR (€)
Oppenheimer
Regulatory Capital Requirements [Line Items]
Required percentage of net capital to aggregate customer-related debit items	$ 0.02
Net capital	423,300,000
Excess capital	$ 397,000,000
Aggregate indebtedness (as a percent)	32.16%
Freedom
Regulatory Capital Requirements [Line Items]
Net capital	$ 4,600,000
Freedom maintain net capital equal to the greater	$ 100,000
Aggregate indebtedness (as a percent)	6.67%
Net capital in excess of minimum required	$ 4,500,000
Oppenheimer Europe Ltd
Regulatory Capital Requirements [Line Items]
Regulatory capital required to be maintained | €		€ 730,000
Oppenheimer Europe Ltd | Basel Three New Requirements
Regulatory Capital Requirements [Line Items]
Common Equity Tier 1 ratio (as a percent)	0.144	0.144
Common Equity Tier 1 ratio required (as a percent)	4.50%	4.50%
Tier 1 Capital ratio (as a percent)	14.40%	14.40%
Tier 1 Capital ratio required (as a percent)	6.00%	6.00%
Total Capital ratio (as a percent)	19.20%	19.20%
Total Capital ratio required (as a percent)	8.00%	8.00%
Oppenheimer Investments Asia Ltd.
Regulatory Capital Requirements [Line Items]
Regulatory capital required to be maintained	$ 385,000
Regulatory capital	3,900,000
Excess Liquid Capital under Hong Kong SFC rules	$ 3,500,000