Net Income per Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
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	$ 207,976	$ 187,811	$ 579,617	$ 503,177
Weighted average limited partnership units outstanding – basic (in units)	268,538,000	268,567,000	269,369,000	268,131,000
Dilutive effect of compensatory options to buy AB Holding Units (in units)	27,000	36,000	23,000	52,000
Weighted average limited partnership units outstanding – diluted (in units)	268,565,000	268,603,000	269,392,000	268,183,000
Basic net income per AB Unit (in dollars per unit)	$ 0.77	$ 0.69	$ 2.13	$ 1.86
Diluted net income per AB Unit (in dollars per unit)	$ 0.77	$ 0.69	$ 2.13	$ 1.86
Anti-dilutive options excluded from diluted net income (in units)	29,056	29,056	29,056	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%