Net Income per Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Limited Partners interest in Company (as a percent)			99.00%
Net income per unit, basic and diluted [Abstract]
Net income attributable to AB Unitholders	$ 264,695	$ 207,976	$ 776,396	$ 579,617
Weighted average limited partnership units outstanding – basic (in units)	271,594,000	268,538,000	272,088,000	269,369,000
Dilutive effect of compensatory options to buy AB Holding Units (in units)	3,000	27,000	14,000	23,000
Weighted average limited partnership units outstanding – diluted (in units)	271,597,000	268,565,000	272,102,000	269,392,000
Basic net income per AB Unit (in dollars per unit)	$ 0.96	$ 0.77	$ 2.82	$ 2.13
Diluted net income per AB Unit (in dollars per unit)	$ 0.96	$ 0.77	$ 2.82	$ 2.13
Anti-dilutive options excluded from diluted net income (in units)	0	29,056	0	29,056
General Partner Interest
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
General partnership interest in Company (percent)			1.00%