Summary of Significant Accounting Policies - Additional Information (Details)			1 Months Ended		3 Months Ended								12 Months Ended
		Feb. 13, 2018 $ / shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2017 USD ($) $ / shares	Sep. 30, 2017 $ / shares	Jun. 30, 2017 $ / shares	Mar. 31, 2017 $ / shares	Dec. 31, 2016 USD ($) $ / shares	Sep. 30, 2016 $ / shares	Jun. 30, 2016 $ / shares	Mar. 31, 2016 $ / shares	Dec. 31, 2017 USD ($) investment shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($)	Jan. 01, 2018 USD ($)
Collateralized Securities Transactions [Abstract]
Cash on deposit with clearing organizations for trade facilitation purposes			$ 42,900,000	$ 41,700,000	$ 42,900,000				$ 41,700,000				$ 42,900,000	$ 41,700,000
SCB LLC held U.S. Treasury Bills			$ 52,600,000	$ 28,900,000	$ 52,600,000				$ 28,900,000				$ 52,600,000	$ 28,900,000
Schedule of Equity Method Investments [Line Items]
Private equity investments owned outside of consolidated venture capital fund | investment													2
Deferred Sales Commissions, Net [Abstract]
Period of time the deferred sales commissions are amortized over for U.S. fund shares													5 years 6 months
Period of time the deferred sales commissions are amortized over for non-U.S. fund shares													4 years
Mutual Fund Underwriting Activities [Abstract]
Period over which receivables from brokers and dealers for sale of shares of company-sponsored mutual funds generally are realized													3 days
Long-term Incentive Compensation Plans [Abstract]
Employee allocation percentage maximum, percent			50.00%		50.00%								50.00%
Long-term incentive cash maximum per employee			$ 250,000		$ 250,000								$ 250,000
Long-term incentive awards vesting periods													4 years
AB Holding Units purchased in periods (in units) | shares													9,300,000	10,500,000
Dollar amount paid for AB Holding Units acquired													$ 220,200,000	$ 236,600,000
Open-market purchases of AB Holding Units (in units) | shares													5,200,000	7,900,000
Dollar amount paid for open-market purchases of AB Holding Units													$ 117,100,000	$ 176,100,000
Restricted AB Holding Units awarded to employees (in units) | shares			6,100,000	6,100,000									8,300,000	7,000,000
Units issued upon exercise of options (in units) | shares													1,179,860	358,262
Proceeds from stock options exercised													$ 20,110,000	$ 6,108,000	$ 9,233,000
Foreign Currency Translations [Abstract]
Net foreign currency transaction gains (losses)													$ (2,900,000)	1,600,000	1,200,000
Cash Distribution [Line Items]
Cash distribution, distribution declared (in dollars per unit) | $ / shares	[1],[2]				$ 0.91	$ 0.58	$ 0.56	$ 0.52	$ 0.73	$ 0.51	$ 0.46	$ 0.45
Percentage of General Partnership interest in company													1.00%
Cash distributions per unit paid to the General Partner and Unitholders (in dollars per unit)													$ 2.39	$ 1.98	$ 2.18
Cash Distribution [Member]
Cash Distribution [Line Items]
Cash distribution, declaration date					Feb. 13, 2018
Percentage of General Partnership interest in company					1.00%
Cash distribution, distribution date					Mar. 08, 2018
Cash distribution, date of record					Feb. 23, 2018
Subsequent Event [Member] | Cash Distribution [Member]
Cash Distribution [Line Items]
Cash distribution, distribution declared (in dollars per unit) | $ / shares		$ 0.91
Employees Based Outside of the United States [Member]
Long-term Incentive Compensation Plans [Abstract]
Employee allocation percentage maximum, percent			100.00%		100.00%								100.00%
Long-term incentive cash maximum per employee			$ 100,000		$ 100,000								$ 100,000
Furniture [Member]
Furniture, Equipment and Leasehold Improvements [Abstract]
Useful Life													8 years
Equipment [Member] | Minimum [Member]
Furniture, Equipment and Leasehold Improvements [Abstract]
Useful Life													3 years
Equipment [Member] | Maximum [Member]
Furniture, Equipment and Leasehold Improvements [Abstract]
Useful Life													6 years
Consolidated Private Equity Fund [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage			10.00%		10.00%								10.00%
Partners' Capital attributable to AB Unitholders [Member] | Subsequent Event [Member] | Accounting Standards Update 2014-09 [Member]
Cash Distribution [Line Items]
Cumulative effect of ASU adoption																$ 35,000,000

[1] Cash distributions reflect the impact of our non-GAAP adjustments.

[2] Declared and paid during the following quarter.