Segment information - Reported Revenue and Profit Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Number Of Reportable Segments Not Disclosed Flag
Total revenue	$ 1,638,071	$ 1,432,496	$ 1,248,825
Compensation expenses	1,016,506	936,813	782,396
Other Segment Items	410,374	389,926	419,659
Pre-tax income	211,191	105,757	46,770
Corporate/Other
Segment Reporting Information [Line Items]
Total revenue	11,353	12,865	12,741
Compensation expenses	116,536	98,974	89,035
Other Segment Items	31,858	34,277	32,510
Pre-tax income	(137,041)	(120,386)	(108,804)
Wealth Management Segment | Operating Segments
Segment Reporting Information [Line Items]
Total revenue	1,035,403	972,052	890,187
Compensation expenses	539,694	514,227	424,031
Other Segment Items	203,644	192,086	247,621
Pre-tax income	292,065	265,739	218,535
Capital Markets | Operating Segments
Segment Reporting Information [Line Items]
Total revenue	591,315	447,579	345,897
Compensation expenses	360,276	323,612	269,330
Other Segment Items	174,872	163,563	139,528
Pre-tax income	$ 56,167	$ (39,596)	$ (62,961)