Net Income per Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Earnings Per Unit [Abstract]
Net income – basic	$ 68,141	$ 90,917	$ 154,069	$ 172,004
Additional allocation of equity in net income attributable to AB resulting from assumed dilutive effect of compensatory options	0	8	2	23
Net income – diluted	$ 68,141	$ 90,925	$ 154,071	$ 172,027
Weighted average units outstanding – basic (in shares)	98,802,000	100,159,000	99,001,000	100,153,000
Dilutive effect of compensatory options (in shares)	0	12,000	2,000	20,000
Weighted average units outstanding – diluted (in shares)	98,802,000	100,171,000	99,003,000	100,173,000
Basic net income per unit (in dollars per share)	$ 0.69	$ 0.91	$ 1.56	$ 1.72
Diluted net income per unit (in dollars per share)	$ 0.69	$ 0.91	$ 1.56	$ 1.72
Anti-dilutive units excluded from diluted net income (in shares)	0	0	0	0