Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	$ 1,071,800	$ 996,007
Not subject to contracts with customers:
Dividend and interest income, net of broker-dealer related interest expense	20,798	22,658
Investment gains	11,743	5,264
Other revenues	(190)	162
Total revenue not from contract with customer	32,351	28,084
Net revenues	1,104,151	1,024,091
Base fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	754,239	692,327
Performance-based fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	30,166	36,580
Bernstein research services
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	96,222	100,038
All-in-management fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	78,424	68,788
12b-1 fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	16,605	15,155
Other distribution fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	70,661	57,135
Shareholder servicing fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	21,663	20,293
Other
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	$ 3,820	$ 5,691