    <SEC-DOCUMENT>0001530950-24-000077-index.html : 20240226
    <SEC-HEADER>0001530950-24-000077.hdr.sgml : 20240226
    <ACCEPTANCE-DATETIME>20240226161722
    ACCESSION NUMBER:		0001530950-24-000077
    CONFORMED SUBMISSION TYPE:	8-K
    PUBLIC DOCUMENT COUNT:		19
    CONFORMED PERIOD OF REPORT:	20240220
    ITEM INFORMATION:		Entry into a Material Definitive Agreement
    ITEM INFORMATION:		Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant
    ITEM INFORMATION:		Financial Statements and Exhibits
    FILED AS OF DATE:		20240226
    DATE AS OF CHANGE:		20240226

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			Post Holdings, Inc.
    		CENTRAL INDEX KEY:			0001530950
    		STANDARD INDUSTRIAL CLASSIFICATION:	GRAIN MILL PRODUCTS [2040]
    		ORGANIZATION NAME:           	04 Manufacturing
    		IRS NUMBER:				453355106
    		STATE OF INCORPORATION:			MO
    		FISCAL YEAR END:			0930

    	FILING VALUES:
    		FORM TYPE:		8-K
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	001-35305
    		FILM NUMBER:		24678959

    	BUSINESS ADDRESS:
    		STREET 1:		2503 S. HANLEY ROAD
    		CITY:			ST. LOUIS
    		STATE:			MO
    		ZIP:			63144
    		BUSINESS PHONE:		314-644-7600

    	MAIL ADDRESS:
    		STREET 1:		2503 S. HANLEY ROAD
    		CITY:			ST. LOUIS
    		STATE:			MO
    		ZIP:			63144
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>8-K
    <SEQUENCE>1
    <FILENAME>post-20240220.htm
    <DESCRIPTION>8-K
    <TEXT>
    Document 1 - file: post-20240220.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-4.1
    <SEQUENCE>2
    <FILENAME>ex4-1xpostxindenturefebrua.htm
    <DESCRIPTION>EX-4.1 - FEBRUARY 2024 INDENTURE
    <TEXT>
    Document 2 - file: ex4-1xpostxindenturefebrua.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-10.1
    <SEQUENCE>3
    <FILENAME>ex10-1xpostxthirdamendtose.htm
    <DESCRIPTION>EX-10.1 - THIRD AMENDMENT TO SECOND AMENDED AND RESTATED CREDIT AGREEMENT
    <TEXT>
    Document 3 - file: ex10-1xpostxthirdamendtose.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-10.2
    <SEQUENCE>4
    <FILENAME>ex10-2xpostxnotessecuritya.htm
    <DESCRIPTION>EX-10.2 - NOTES SECURITY AGREEMENT
    <TEXT>
    Document 4 - file: ex10-2xpostxnotessecuritya.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-10.3
    <SEQUENCE>5
    <FILENAME>ex10-3xpostxparipassuinter.htm
    <DESCRIPTION>EX-10.3 - PARI PASSU INTERCREDITOR AGREEMENT
    <TEXT>
    Document 5 - file: ex10-3xpostxparipassuinter.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.SCH
    <SEQUENCE>6
    <FILENAME>post-20240220.xsd
    <DESCRIPTION>XBRL TAXONOMY EXTENSION SCHEMA DOCUMENT
    <TEXT>
    Document 6 - file: post-20240220.xsd

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.LAB
    <SEQUENCE>7
    <FILENAME>post-20240220_lab.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION LABEL LINKBASE DOCUMENT
    <TEXT>
    Document 7 - file: post-20240220_lab.xml

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    <DOCUMENT>
    <TYPE>EX-101.PRE
    <SEQUENCE>8
    <FILENAME>post-20240220_pre.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE DOCUMENT
    <TEXT>
    Document 8 - file: post-20240220_pre.xml

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>9
    <FILENAME>post-20240220_g1.jpg
    <TEXT>
    Document 9 - file: post-20240220_g1.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>10
    <FILENAME>R1.htm
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 10 - file: R1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EXCEL
    <SEQUENCE>12
    <FILENAME>Financial_Report.xlsx
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 12 - file: Financial_Report.xlsx

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>13
    <FILENAME>Show.js
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 13 - file: Show.js

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>14
    <FILENAME>report.css
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 14 - file: report.css

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>16
    <FILENAME>FilingSummary.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 16 - file: FilingSummary.html

    Document 16 - RAW XML: FilingSummary.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>JSON
    <SEQUENCE>18
    <FILENAME>MetaLinks.json
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 18 - file: MetaLinks.json

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    <DOCUMENT>
    <TYPE>ZIP
    <SEQUENCE>19
    <FILENAME>0001530950-24-000077-xbrl.zip
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 19 - file: 0001530950-24-000077-xbrl.zip

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    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>20
    <FILENAME>post-20240220_htm.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 20 - file: post-20240220_htm.html

    Document 20 - RAW XML: post-20240220_htm.xml

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