Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	$ 982,926	$ 1,005,760	$ 1,978,933	$ 2,141,613
Not subject to contracts with customers:
Dividend and interest income, net of broker-dealer related interest expense	24,744	13,666	47,402	22,292
Investment gains (losses)	670	(48,220)	5,934	(87,244)
Other revenues	116	238	278	470
Total revenue not from contract with customer	25,530	(34,316)	53,614	(64,482)
Net revenues	1,008,456	971,444	2,032,547	2,077,131
Base fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	703,371	696,685	1,395,699	1,444,498
Performance-based fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	18,307	22,791	54,886	98,760
Bernstein research services
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	91,847	106,442	191,885	224,249
All-in-management fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	70,849	73,399	139,637	154,620
12b-1 fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	15,778	17,436	30,933	36,953
Other distribution fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	58,171	62,295	115,306	129,898
Shareholder servicing fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	20,801	22,394	41,094	44,808
Other
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	$ 3,802	$ 4,318	$ 9,493	$ 7,827