Business Segment Information - Net Revenues Derived From Investment Management and Related Services (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Revenues:
Total revenues	$ 4,593,648	$ 4,559,652	$ 4,262,864
Less: Broker-dealer related Interest expense	62,996	84,513	107,541
Net revenues	4,530,652	4,475,139	4,155,323
Reportable Segment
Revenues:
Total revenues	4,593,648	4,559,652	4,262,864
Less: Broker-dealer related Interest expense	62,996	84,513	107,541
Net revenues	4,530,652	4,475,139	4,155,323
Institutions | Reportable Segment
Revenues:
Total revenues	683,543	700,796	666,670
Retail | Reportable Segment
Revenues:
Total revenues	2,470,403	2,311,317	1,926,020
Private Wealth Management | Reportable Segment
Revenues:
Total revenues	1,278,760	1,245,891	1,052,843
Bernstein Research Services | Reportable Segment
Revenues:
Total revenues	0	96,222	386,142
Other | Reportable Segment
Revenues:
Total revenues	$ 160,942	$ 205,426	$ 231,189