Business Segment Information - Net Revenues Derived From Investment Management, Research and Related Services (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Revenues:
Total revenues	$ 1,152,350	$ 1,106,703	$ 3,355,043	$ 3,284,327
Less: Broker-dealer related Interest expense	15,203	21,214	48,382	66,744
Net revenues	1,137,147	1,085,489	3,306,661	3,217,583
Reportable Segment
Revenues:
Total revenues	1,152,350	1,106,703	3,355,043	3,284,326
Less: Broker-dealer related Interest expense	15,203	21,214	48,382	66,743
Net revenues	1,137,147	1,085,489	3,306,661	3,217,583
Institutions | Reportable Segment
Revenues:
Total revenues	161,090	167,376	496,113	483,428
Retail | Reportable Segment
Revenues:
Total revenues	631,769	593,323	1,834,917	1,696,171
Private Wealth Management | Reportable Segment
Revenues:
Total revenues	313,191	293,527	909,416	858,973
Bernstein Research Services | Reportable Segment
Revenues:
Total revenues	0	0	0	96,222
Other | Reportable Segment
Revenues:
Total revenues	$ 46,300	$ 52,477	$ 114,597	$ 149,532