Net Income per Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 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	$ 194,320	$ 149,114
Weighted average limited partnership units outstanding – basic (in units)	270,498,000	267,336,000
Dilutive effect of compensatory options to buy AB Holding Units (in units)	32,000	72,000
Weighted average limited partnership units outstanding – diluted (in units)	270,530,000	267,408,000
Basic net income per AB Unit (in dollars per unit)	$ 0.71	$ 0.55
Diluted net income per AB Unit (in dollars per unit)	$ 0.71	$ 0.55
Options excluded from diluted net income per unit computation due to their anti-dilutive effect (in units)	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%