Revenue Recognition (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	$ 4,482,269	$ 4,406,318	$ 4,048,736
Not subject to contracts with customers:
Dividend and interest income, net of interest expense	77,372	80,800	91,902
Investment (losses) gains	(30,846)	(13,486)	14,206
Other revenues	1,857	1,507	479
Total revenue not from contract with customer	48,383	68,821	106,587
Net revenues	4,530,652	4,475,139	4,155,323
Base fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	3,346,239	3,171,175	2,830,557
Performance-based fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	185,251	270,964	144,911
Bernstein research services
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	0	96,222	386,142
All-in-management fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	358,877	337,999	284,057
12b-1 fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	63,050	67,611	63,127
Other distribution fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	396,517	321,060	239,079
Shareholder servicing fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	82,771	89,195	83,802
JV related revenues
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	36,341	37,775	0
Other
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	$ 13,223	$ 14,317	$ 17,061