Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Cash Flows from Operating Activities:
Net earnings including redeemable noncontrolling interest	$ 246.5	$ 165.5	$ 116.0
Adjustments to reconcile net earnings including redeemable noncontrolling interest to net cash provided by operating activities:
Depreciation and amortization	36.5	28.3	21.3
Loss on extinguishment of debt, net	0.0	0.0	17.6
Non-cash stock-based compensation expense	21.0	14.2	9.8
Deferred income taxes	(8.7)	(6.0)	(4.0)
Other, net	1.9	1.2	1.4
Other changes in operating assets and liabilities:
(Increase) decrease in receivables	(51.6)	5.5	(70.7)
(Increase) decrease in inventories	(90.9)	6.4	(83.9)
(Increase) decrease in prepaid expenses and other current assets	(1.7)	(0.8)	1.1
(Increase) decrease in other assets	(2.5)	(1.8)	2.3
Increase in accounts payable and other current liabilities	49.2	3.1	10.3
Decrease in non-current liabilities	(0.1)	0.0	(0.2)
Net Cash Provided by Operating Activities	199.6	215.6	21.0
Cash Flows from Investing Activities:
Additions to property	(1.8)	(1.8)	(1.8)
Net Cash Used in Investing Activities	(1.8)	(1.8)	(1.8)
Cash Flows from Financing Activities:
Proceeds from issuance of long-term debt	0.0	115.0	164.0
Repayments of long-term debt	(25.0)	(189.0)	(674.9)
Payment of merger consideration	0.0	0.0	(115.5)
Purchases of treasury stock	(146.6)	(125.5)	(42.8)
Payments of debt issuance, extinguishment costs and deferred financing fees	0.0	0.0	(11.9)
Distributions from Post Holdings, Inc., net	0.0	0.0	547.2
Other, net	(3.5)	(2.2)	(1.1)
Net Cash Used in Financing Activities	(175.1)	(201.7)	(135.0)
Effect of Exchange Rate Changes on Cash and Cash Equivalents	0.0	0.5	(1.0)
Net Increase (Decrease) in Cash and Cash Equivalents	22.7	12.6	(116.8)
Cash and Cash Equivalents, Beginning of Year	48.4	35.8	152.6
Cash and Cash Equivalents, End of Year	71.1	48.4	35.8
Noncash Investing and Financing Items [Abstract]
Debt issued to Post Holdings, Inc. in connection with Spin-off	$ 0.0	$ 0.0	$ 840.0