    <SEC-DOCUMENT>0000719220-24-000085-index.html : 20241017
    <SEC-HEADER>0000719220-24-000085.hdr.sgml : 20241017
    <ACCEPTANCE-DATETIME>20241017073022
    ACCESSION NUMBER:		0000719220-24-000085
    CONFORMED SUBMISSION TYPE:	8-K
    PUBLIC DOCUMENT COUNT:		28
    CONFORMED PERIOD OF REPORT:	20241017
    ITEM INFORMATION:		Results of Operations and Financial Condition
    ITEM INFORMATION:		Regulation FD Disclosure
    ITEM INFORMATION:		Financial Statements and Exhibits
    FILED AS OF DATE:		20241017
    DATE AS OF CHANGE:		20241017

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			S&T BANCORP INC
    		CENTRAL INDEX KEY:			0000719220
    		STANDARD INDUSTRIAL CLASSIFICATION:	STATE COMMERCIAL BANKS [6022]
    		ORGANIZATION NAME:           	02 Finance
    		IRS NUMBER:				251434426
    		STATE OF INCORPORATION:			PA
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		8-K
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	000-12508
    		FILM NUMBER:		241375930

    	BUSINESS ADDRESS:
    		STREET 1:		800 PHILADELPHIA STREET
    		STREET 2:		PO BOX 190
    		CITY:			INDIANA
    		STATE:			PA
    		ZIP:			15701
    		BUSINESS PHONE:		724-427-2347

    	MAIL ADDRESS:
    		STREET 1:		800 PHILADELPHIA STREET
    		STREET 2:		PO BOX 190
    		CITY:			INDIANA
    		STATE:			PA
    		ZIP:			15701
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>8-K
    <SEQUENCE>1
    <FILENAME>stba-20241017.htm
    <DESCRIPTION>8-K
    <TEXT>
    Document 1 - file: stba-20241017.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.1
    <SEQUENCE>2
    <FILENAME>stba-ex991earningspressrel.htm
    <DESCRIPTION>EX-99.1
    <TEXT>
    Document 2 - file: stba-ex991earningspressrel.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.2
    <SEQUENCE>3
    <FILENAME>stbancorpincthirdquarter.htm
    <DESCRIPTION>EX-99.2
    <TEXT>
    Document 3 - file: stbancorpincthirdquarter.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.SCH
    <SEQUENCE>4
    <FILENAME>stba-20241017.xsd
    <DESCRIPTION>XBRL TAXONOMY EXTENSION SCHEMA DOCUMENT
    <TEXT>
    Document 4 - file: stba-20241017.xsd

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    <DOCUMENT>
    <TYPE>EX-101.LAB
    <SEQUENCE>5
    <FILENAME>stba-20241017_lab.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION LABEL LINKBASE DOCUMENT
    <TEXT>
    Document 5 - file: stba-20241017_lab.xml

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    <DOCUMENT>
    <TYPE>EX-101.PRE
    <SEQUENCE>6
    <FILENAME>stba-20241017_pre.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE DOCUMENT
    <TEXT>
    Document 6 - file: stba-20241017_pre.xml

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>7
    <FILENAME>earn_image1a15.jpg
    <TEXT>
    Document 7 - file: earn_image1a15.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>8
    <FILENAME>stbancorpincthirdquarter001.jpg
    <TEXT>
    Document 8 - file: stbancorpincthirdquarter001.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>9
    <FILENAME>stbancorpincthirdquarter002.jpg
    <TEXT>
    Document 9 - file: stbancorpincthirdquarter002.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>10
    <FILENAME>stbancorpincthirdquarter003.jpg
    <TEXT>
    Document 10 - file: stbancorpincthirdquarter003.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>11
    <FILENAME>stbancorpincthirdquarter004.jpg
    <TEXT>
    Document 11 - file: stbancorpincthirdquarter004.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>12
    <FILENAME>stbancorpincthirdquarter005.jpg
    <TEXT>
    Document 12 - file: stbancorpincthirdquarter005.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>13
    <FILENAME>stbancorpincthirdquarter006.jpg
    <TEXT>
    Document 13 - file: stbancorpincthirdquarter006.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>14
    <FILENAME>stbancorpincthirdquarter007.jpg
    <TEXT>
    Document 14 - file: stbancorpincthirdquarter007.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>15
    <FILENAME>stbancorpincthirdquarter008.jpg
    <TEXT>
    Document 15 - file: stbancorpincthirdquarter008.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>16
    <FILENAME>stbancorpincthirdquarter009.jpg
    <TEXT>
    Document 16 - file: stbancorpincthirdquarter009.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>17
    <FILENAME>stbancorpincthirdquarter010.jpg
    <TEXT>
    Document 17 - file: stbancorpincthirdquarter010.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>18
    <FILENAME>stbancorpincthirdquarter011.jpg
    <TEXT>
    Document 18 - file: stbancorpincthirdquarter011.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>19
    <FILENAME>stbancorpincthirdquarter012.jpg
    <TEXT>
    Document 19 - file: stbancorpincthirdquarter012.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>21
    <FILENAME>R1.htm
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 21 - file: R1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EXCEL
    <SEQUENCE>22
    <FILENAME>Financial_Report.xlsx
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 22 - file: Financial_Report.xlsx

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>23
    <FILENAME>Show.js
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 23 - file: Show.js

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    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>24
    <FILENAME>report.css
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 24 - file: report.css

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>26
    <FILENAME>FilingSummary.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 26 - file: FilingSummary.html

    Document 26 - RAW XML: FilingSummary.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>JSON
    <SEQUENCE>28
    <FILENAME>MetaLinks.json
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 28 - file: MetaLinks.json

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    <DOCUMENT>
    <TYPE>ZIP
    <SEQUENCE>29
    <FILENAME>0000719220-24-000085-xbrl.zip
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 29 - file: 0000719220-24-000085-xbrl.zip

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    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>30
    <FILENAME>stba-20241017_htm.xml
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    <TEXT>
    Document 30 - file: stba-20241017_htm.html

    Document 30 - RAW XML: stba-20241017_htm.xml

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