Income taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule Of Income Taxes [Line Items]
Effective income tax (as a percent)	29.90%	32.60%	35.30%
Net change in total valuation allowance	$ 2,500
Unrecognized tax benefits	1,530	$ 1,258	$ 1,236	$ 1,072
Unrecognized tax benefit that would impact tax rate	1,200	994
Additions for tax positions of prior years	823	217	224
Settlements with taxing authorities	140	59	60
Unrecognized tax benefits, penalties and interest tax expense	55	3	$ 107
Income tax-related interest payable	269	$ 325
State and Local Jurisdiction
Schedule Of Income Taxes [Line Items]
Additions for tax positions of prior years	800
Settlements with taxing authorities	600
Oppenheimer Israel (OPCO) Ltd.
Schedule Of Income Taxes [Line Items]
Net operating loss carryforward	2,700
Oppenheimer Europe [Member]
Schedule Of Income Taxes [Line Items]
Net operating loss carryforward	$ 13,100