Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue
Net Sales	$ 494.6	$ 385.6	$ 925.0	$ 748.3
Shakes and other beverages
Disaggregation of Revenue
Net Sales	397.9	299.9	748.1	596.9
Powders
Disaggregation of Revenue
Net Sales	84.1	73.8	153.8	129.9
Other
Disaggregation of Revenue
Net Sales	$ 12.6	$ 11.9	$ 23.1	$ 21.5