Long-Term Incentive Compensation Plans - Option Plan Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Options to Buy AB Holding Units
Granted (in units)	0	0	0
Exercised (in units)	(143,211)	(5,182)
Option Awards
Options to Buy AB Holding Units
Beginning balance (in units)	148,985
Granted (in units)	0
Exercised (in units)	(143,211)
Forfeited (in units)	0
Expired (in units)	0
Ending balance (in units)	5,774	148,985
Exercisable (in units)	5,774
Vested or expected to vest (in units)	5,774
Weighted Average Exercise  Price Per Option
Beginning balance (in dollars per unit)	$ 23.61
Granted, Weighted Average Exercise Price Per Option (in dollars per unit)	0
Exercised, Weighted Average Exercise Price Per Option (in dollars per unit)	23.75
Forfeited, Weighted Average Exercise Price Per Option (in dollars per unit)	0
Expired, Weighted Average Exercise Price Per Option (in dollars per unit)	0
Ending balance (in dollars per unit)	20.12	$ 23.61
Exercisable, Weighted Average Exercise Price Per Option (in dollars per unit)	20.12
Vested or expected to vest, Weighted Average Exercise Price Per Option (in dollars per unit)	$ 20.12
Weighted Average Remaining Contractual Term (Years)
Outstanding, Weighted Average Remaining Contractual Term	3 months 29 days	1 year 2 months 12 days
Exercisable, Weighted Average Remaining Contractual Term	3 months 29 days
Vested or expected to vest, Weighted Average Remaining Contractual Term	3 months 29 days
Outstanding, Aggregate Intrinsic Value	$ 165.8
Exercisable, Aggregate Intrinsic Value	165.8
Vested or expected to vest, Aggregate Intrinsic Value	$ 165.8