Related Party Transactions - Revenues for Services Provided (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Related Party Transaction [Line Items]
Other revenues	$ 142,794	$ 101,342	$ 105,544
Mutual Funds
Related Party Transaction [Line Items]
Revenues	2,396,756	2,039,401	2,130,998
Other revenues	7,400	9,398	8,366
Investment advisory and services fees
Related Party Transaction [Line Items]
Revenues	3,442,139	2,975,468	2,971,038
Investment advisory and services fees | Mutual Funds
Related Party Transaction [Line Items]
Revenues	1,597,253	1,377,916	1,452,885
Distribution revenues | Mutual Funds
Related Party Transaction [Line Items]
Revenues	711,156	575,647	590,580
Shareholder servicing fees | Mutual Funds
Related Party Transaction [Line Items]
Revenues	80,947	76,440	79,167
Bernstein research services
Related Party Transaction [Line Items]
Revenues	$ 96,222	$ 386,142	$ 416,273