Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash Flows from Operating Activities:
Net Earnings Including Redeemable Noncontrolling Interest	$ 32.9	$ 31.8
Adjustments to reconcile net earnings including redeemable noncontrolling interest to net cash provided by (used in) operating activities:
Depreciation and amortization	6.7	6.4
Unrealized gain on interest rate swaps	(0.7)	0.0
Non-cash stock-based compensation expense	1.1	0.3
Deferred income taxes	0.7	0.2
Other, net	0.8	1.1
Other changes in operating assets and liabilities:
Increase in receivables	(39.9)	(25.3)
Decrease (increase) in inventories	14.5	(11.8)
Increase in prepaid expenses and other current assets	(6.1)	(5.8)
Decrease in other assets	0.7	0.8
Increase (decrease) in accounts payable and other current liabilities	12.3	(22.5)
Increase (decrease) in non-current liabilities	0.3	(0.1)
Net Cash Provided by (Used in) Operating Activities	23.3	(24.9)
Cash Flows from Investing Activities:
Additions to property	0.0	(0.7)
Net Cash Used in Investing Activities	0.0	(0.7)
Cash Flows from Financing Activities:
Proceeds from issuance of long-term debt	20.0	806.0
Proceeds from issuance of common stock, net of issuance costs	0.0	524.4
Repayments of long-term debt	(37.5)	(1,265.0)
Payments of debt issuance costs and deferred financing fees	0.0	(9.6)
Distributions to Post Holdings, Inc., net	(3.6)	(5.9)
Other, net	(0.9)	0.0
Net Cash (Used in) Provided by Financing Activities	(22.0)	49.9
Effect of Exchange Rate Changes on Cash and Cash Equivalents	0.8	0.1
Net Increase in Cash and Cash Equivalents	2.1	24.4
Cash and Cash Equivalents, Beginning of Year	48.7	5.5
Cash and Cash Equivalents, End of Period	$ 50.8	$ 29.9