Long-Term Incentive Compensation Plans - Schedule of Grant Details of Restricted AB Holding Units (Details) - Restricted Stock Units (RSUs) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in units)	6,984,456
Weighted average grant date fair value (in dollars per unit)	$ 39.68
Employment and Separation Agreements
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in units)	3,400,000	400,000	1,900,000
Compensation Expense	$ 40.9	$ 32.1	$ 36.7
Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in units)	35,358	50,232	45,420
Weighted average grant date fair value (in dollars per unit)	$ 44.29	$ 23.69	$ 29.33
Compensation Expense	$ 1.6	$ 1.2	$ 1.3
Minimum | Employment and Separation Agreements
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in dollars per unit)	$ 29.06	$ 18.80	$ 27.32
Maximum | Employment and Separation Agreements
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in dollars per unit)	$ 53.86	$ 35.42	$ 30.85