Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	$ 1,005,760	$ 1,064,133	$ 2,141,613	$ 2,061,598
Not subject to contracts with customers:
Dividend and interest income, net of interest expense	13,666	7,924	22,292	15,464
Investment (losses) gains	(48,220)	4,181	(87,244)	6,109
Other revenues	238	584	470	917
Total revenue not from contract with customer	(34,316)	12,689	(64,482)	22,490
Net revenues	971,444	1,076,822	2,077,131	2,084,088
Base fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	696,685	723,717	1,444,498	1,411,408
Performance-based fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	22,791	53,907	98,760	69,682
Bernstein research services
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	106,442	105,655	224,249	224,676
All-in-management fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	73,399	86,073	154,620	171,255
12b-1 fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	17,436	20,653	36,953	40,687
Other distribution fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	62,295	48,812	129,898	91,196
Shareholder servicing fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	22,394	22,383	44,808	44,078
Other
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	$ 4,318	$ 2,933	$ 7,827	$ 8,616