Net Income per Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Unit [Abstract]
Net income – basic	$ 43,910	$ 54,592
Additional allocation of equity in net income attributable to AB resulting from assumed dilutive effect of compensatory options	176	153
Net income – diluted	$ 44,086	$ 54,745
Weighted average units outstanding – basic (in units)	96,238,000	99,596,000
Dilutive effect of compensatory options (in units)	534,000	400,000
Weighted average units outstanding – diluted (in units)	96,772,000	99,996,000
Basic net income per unit (in dollars per unit)	$ 0.46	$ 0.55
Diluted net income per unit (in dollars per unit)	$ 0.46	$ 0.55
Anti-dilutive units excluded from diluted net income computation (in units)	2,437,307	2,888,476