Net Income per Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 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	$ 181,665	$ 135,103	$ 365,861	$ 275,040
Weighted average limited partnership units outstanding – basic (in units)	270,564,000	268,302,000	269,870,000	268,391,000
Dilutive effect of compensatory options to buy AB Holding Units (in units)	272,000	430,000	303,000	482,000
Weighted average limited partnership units outstanding – diluted (in units)	270,836,000	268,732,000	270,173,000	268,873,000
Basic net income per AB Unit (in dollars per unit)	$ 0.66	$ 0.50	$ 1.34	$ 1.01
Diluted net income per AB Unit (in dollars per unit)	$ 0.66	$ 0.50	$ 1.34	$ 1.01
Options excluded from diluted net income per unit computation due to their anti-dilutive effect (in units)	850,155	2,507,179	1,211,906	2,452,633