Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	$ 907,320	$ 769,186
Dividend and interest income, net of interest expense	11,146	10,183
Investment (losses) gains	(44,306)	15,735
Other revenues	(4)	358
Revenue not subject to contract with customer	(33,164)	26,276
Net revenues	874,156	795,462
Base fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	613,587	552,230
Performance-based fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	8,138	4,364
Bernstein research services
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	129,223	90,235
All-in-management fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	86,357	61,773
12b-1 fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	19,453	19,586
Other
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	25,047	19,150
Shareholder servicing fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	20,843	17,830
Other
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	$ 4,672	$ 4,018

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Noninterest Income, Other Operating Income, Excluding Revenue From Contract With Customer

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Amount of realized and unrealized gain (loss), from the firm's direct investment activity, conducted separately from customer trading activities, and includes, but is not limited to, investments in private equity, alternative investment products, real estate, and exchanges and memberships.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income after deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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