Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	$ 1,083,871	$ 1,071,800
Not subject to contracts with customers:
Dividend and interest income, net of broker-dealer related interest expense	16,833	20,798
Investment (losses) gains	(20,538)	11,743
Other revenues	441	(190)
Total revenue not from contract with customer	(3,264)	32,351
Net revenues	1,080,607	1,104,151
Base fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	817,866	754,239
Performance-based fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	37,246	30,166
Bernstein research services
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	0	96,222
All-in-management fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	88,444	78,424
12b-1 fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	16,252	16,605
Other distribution fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	94,324	70,661
Shareholder servicing fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	16,642	21,663
JV related revenues
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	9,334	0
Other
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	$ 3,763	$ 3,820