Intangible Assets, net (Details) - USD ($) $ in Millions	Dec. 31, 2020	Sep. 30, 2020
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	$ 425.9	$ 425.9
Finite-lived intangible assets, accumulated amortization	(157.5)	(151.6)
Finite-lived intangible assets, net	268.4	274.3
Customer relationships
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	209.4	209.4
Finite-lived intangible assets, accumulated amortization	(80.0)	(76.9)
Finite-lived intangible assets, net	129.4	132.5
Customer relationships | Supreme Protein
Finite-Lived Intangible Assets
Finite-lived intangible assets, net	18.7
Trademarks and brands
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	213.4	213.4
Finite-lived intangible assets, accumulated amortization	(74.4)	(71.6)
Finite-lived intangible assets, net	139.0	141.8
Trademarks and brands | Supreme Protein
Finite-Lived Intangible Assets
Finite-lived intangible assets, net	11.8
Other intangible assets
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	3.1	3.1
Finite-lived intangible assets, accumulated amortization	(3.1)	(3.1)
Finite-lived intangible assets, net	$ 0.0	$ 0.0