Related Party Transactions - Revenues for Services Provided (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Other revenues	$ 108,409	$ 104,703	$ 97,559
Mutual Funds
Related Party Transaction [Line Items]
Revenue subject to contracts with customers	2,375,944	1,972,531	1,799,541
Other revenues	8,364	8,314	7,303
Investment advisory and services fees
Related Party Transaction [Line Items]
Revenue subject to contracts with customers	3,194,524	2,595,436	2,472,044
Investment advisory and services fees | Mutual Funds
Related Party Transaction [Line Items]
Revenue subject to contracts with customers	1,644,757	1,368,484	1,275,677
Distribution revenues | Mutual Funds
Related Party Transaction [Line Items]
Revenue subject to contracts with customers	637,076	516,336	441,437
Shareholder servicing fees | Mutual Funds
Related Party Transaction [Line Items]
Revenue subject to contracts with customers	85,745	79,394	75,122
Bernstein research services
Related Party Transaction [Line Items]
Revenue subject to contracts with customers	452,017	459,744	407,911
Bernstein research services | Mutual Funds
Related Party Transaction [Line Items]
Revenue subject to contracts with customers	$ 2	$ 3	$ 2