Net Income per Unit - Summary of Earnings Per Unit, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Earnings Per Unit [Abstract]
Net income attributable to AB Unitholders	$ 295,485	$ 220,799
Weighted average limited partnership Units outstanding – basic (in shares)	293,729	292,187
Weighted average limited partnership Units outstanding – diluted (in shares)	293,729	292,187
Net income per AB Unit - basic (in dollars per share)	$ 1.00	$ 0.75
Net income per AB Unit - diluted (in dollars per share)	$ 1.00	$ 0.75