Net Income per Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Unit [Abstract]
General partnership interest in Company (percent)			1.00%
Limited Partners interest in Company (as a percent)			99.00%
Net income per unit, basic and diluted [Abstract]
Net income attributable to AB Unitholders	$ 203,674	$ 140,954	$ 569,535	$ 415,994
Weighted average limited partnership units outstanding – basic (in units)	269,603,000	265,585,000	269,783,000	267,448,000
Dilutive effect of compensatory options to buy AB Holding Units (in units)	245,000	400,000	282,000	455,000
Weighted average limited partnership units outstanding – diluted (in units)	269,848,000	265,985,000	270,065,000	267,903,000
Basic net income per AB Unit (in dollars per unit)	$ 0.75	$ 0.53	$ 2.09	$ 1.54
Diluted net income per AB Unit (in dollars per unit)	$ 0.75	$ 0.52	$ 2.09	$ 1.54
Options excluded from diluted net income per unit computation due to their anti-dilutive effect (in units)	824,245	2,427,527	844,973	2,427,527