Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Cash Flows from Operating Activities:
Net earnings including redeemable noncontrolling interest	$ 100.1	$ 123.1	$ 96.1
Adjustments to reconcile net earnings including redeemable noncontrolling interest to net cash provided by operating activities:
Depreciation and amortization	25.3	25.3	25.9
Unrealized loss on interest rate swaps	1.0	0.0	0.0
Non-cash stock-based compensation expense	2.5	0.0	0.0
Deferred income taxes	(3.3)	0.5	(8.6)
Other, net	4.9	12.6	4.6
Other changes in operating assets and liabilities:
(Increase) decrease in receivables	(14.2)	18.5	(24.3)
(Increase) decrease in inventories	(11.5)	(77.2)	24.1
(Increase) decrease in prepaid expenses and other current assets	(0.2)	(3.6)	5.3
Decrease (increase) in other assets	2.6	0.0	(0.1)
Decrease (increase) in accounts payable and other current liabilities	(12.1)	(1.9)	17.4
Increase (decrease) in non-current liabilities	2.1	1.0	0.8
Net Cash Provided by Operating Activities	97.2	98.3	141.2
Cash Flows from Investing Activities:
Additions to property	(2.1)	(3.2)	(5.0)
Net Cash Used in Investing Activities	(2.1)	(3.2)	(5.0)
Cash Flows from Financing Activities:
Proceeds from issuance of long-term debt	881.0	0.0	0.0
Proceeds from issuance of common stock, net of issuance costs	524.4	0.0	0.0
Repayments of long-term debt	(1,416.3)	0.0	0.0
Payments of debt issuance costs and deferred financing fees	(9.6)	0.0	0.0
Distributions to Post Holdings, Inc., net	(32.1)	(100.2)	(133.0)
Net Cash Provided by (Used in) Financing Activities	(52.6)	(100.2)	(133.0)
Effect of exchange rate changes on cash and cash equivalents	0.7	(0.3)	(0.1)
Cash and Cash Equivalents,Period Increase (Decrease), Including Exchange Rate Effect, Total	43.2	(5.4)	3.1
Cash and Cash Equivalents, Beginning of Period	5.5	10.9	7.8
Cash and Cash Equivalents, End of Period	$ 48.7	$ 5.5	$ 10.9