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Number of common units issued of limited liability company (LLC).

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PHPC (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	8 Months Ended	9 Months Ended		12 Months Ended
PHPC (Details) - USD ($) $ / shares in Units, $ in Millions	Jun. 30, 2023	May 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Sep. 30, 2021	Mar. 31, 2023	Sep. 30, 2022
Schedule of Equity Method Investments
Investments held in trust		$ 353.4
Redeemable noncontrolling interest		312.5
Redemption of Post Holdings Partnering Corporation Series A common stock			$ 0.0	$ 312.5
Maximum interest to pay dissolution expenses							$ 0.1
Gain on write-off of underwriting commissions		$ 10.7
Return of subsidiary investments held in trust account			$ 0.0	345.0
Initial public offering costs					$ 17.9
Deferred Offering Costs							$ 10.7
Series A common stock included in each unit							1
PHPC Units
Schedule of Equity Method Investments
Common Unit, Issued					34,500,000
Share Price							$ 10.00
Redemption Price		$ 10.24
PHPC Warrants
Schedule of Equity Method Investments
Class of Warrant or Right, Exercise Price of Warrants or Rights							11.50
PHPC Private Placement Units
Schedule of Equity Method Investments
Share Price							$ 10.00
PHPC Sponsor \| PHPC Private Placement Units
Schedule of Equity Method Investments
Common Unit, Issued					1,100,000
PHPC \| PHPC Units
Schedule of Equity Method Investments
Proceeds from initial public offering					$ 345.0
PHPC \| PHPC Private Placement Units
Schedule of Equity Method Investments
Proceeds from Issuance of Private Placement					$ 10.9
PHPC \| Post Holdings, Inc.
Schedule of Equity Method Investments
Noncontrolling Interest, Ownership Percentage by Parent		31.00%
PHPC \| Public Shareholders
Schedule of Equity Method Investments
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		69.00%
PHPC Sponsor \| Series F Common Stock
Schedule of Equity Method Investments
Common Stock, Shares, Outstanding							8,600,000
PHPC Sponsor \| PHPC Units
Schedule of Equity Method Investments
Common Unit, Issued		4,000,000.0			4,000,000.0
Return of subsidiary investments held in trust account		$ 40.9
Redeemable Noncontrolling Interest
Schedule of Equity Method Investments
Net earnings attributable to redeemable noncontrolling interest	$ 9.3			12.1
Noncontrolling interest, Redemption value adjustment	(1.9)			(5.9)
Redeemable noncontrolling interest	0.0			0.0		$ 310.6	$ 306.6
Redemption of Post Holdings Partnering Corporation Series A common stock	(312.5)			(312.5)
Noncontrolling Interest, Change in Redemption Value	$ 7.4			$ 6.2