Net Income per Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Earnings Per Unit [Abstract]
Net income – basic	$ 85,928	$ 81,087
Additional allocation of equity in net income attributable to AB resulting from assumed dilutive effect of compensatory options	2	18
Net income – diluted	$ 85,930	$ 81,105
Weighted average units outstanding – basic (in shares)	99,202,000	100,146,000
Dilutive effect of compensatory options (in shares)	3,000	32,000
Weighted average units outstanding – diluted (in shares)	99,205,000	100,178,000
Basic net income per unit (in dollars per share)	$ 0.87	$ 0.81
Diluted net income per unit (in dollars per share)	$ 0.87	$ 0.81
Anti-dilutive units excluded from diluted net income (in shares)	0	0