    <SEC-DOCUMENT>0001140361-24-016502-index.html : 20240329
    <SEC-HEADER>0001140361-24-016502.hdr.sgml : 20240329
    <ACCEPTANCE-DATETIME>20240329120144
    ACCESSION NUMBER:		0001140361-24-016502
    CONFORMED SUBMISSION TYPE:	DEF 14A
    PUBLIC DOCUMENT COUNT:		54
    CONFORMED PERIOD OF REPORT:	20240515
    FILED AS OF DATE:		20240329
    DATE AS OF CHANGE:		20240329

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			COMMUNITY BANK SYSTEM, INC.
    		CENTRAL INDEX KEY:			0000723188
    		STANDARD INDUSTRIAL CLASSIFICATION:	NATIONAL COMMERCIAL BANKS [6021]
    		ORGANIZATION NAME:           	02 Finance
    		IRS NUMBER:				161213679
    		STATE OF INCORPORATION:			DE
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		DEF 14A
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	001-13695
    		FILM NUMBER:		24802854

    	BUSINESS ADDRESS:
    		STREET 1:		5790 WIDEWATERS PKWY
    		CITY:			DEWITT
    		STATE:			NY
    		ZIP:			13214
    		BUSINESS PHONE:		8007242262

    	MAIL ADDRESS:
    		STREET 1:		5790 WIDEWATERS PARKWAY
    		CITY:			DEWITT
    		STATE:			NY
    		ZIP:			13214

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	COMMUNITY BANK NA, a subsidiary of Community Bank System Inc
    		DATE OF NAME CHANGE:	20130729

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	COMMUNITY BANK NA, a subsidiary of Community Bank System Inc.
    		DATE OF NAME CHANGE:	20130726

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	COMMUNITY BANK SYSTEM INC
    		DATE OF NAME CHANGE:	19920703
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>DEF 14A
    <SEQUENCE>1
    <FILENAME>ny20019223x1_def14a.htm
    <DESCRIPTION>DEFINITIVE PROXY STATEMENTS
    <TEXT>
    Document 1 - file: ny20019223x1_def14a.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.SCH
    <SEQUENCE>2
    <FILENAME>cbu-20240515.xsd
    <DESCRIPTION>INLINE XBRL TAXONOMY EXTENSION - SCHEMA
    <TEXT>
    Document 2 - file: cbu-20240515.xsd

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.DEF
    <SEQUENCE>3
    <FILENAME>cbu-20240515_def.xml
    <DESCRIPTION>INLINE XBRL TAXONOMY EXTENSION - DEFINITION LINKBASE
    <TEXT>
    Document 3 - file: cbu-20240515_def.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.LAB
    <SEQUENCE>4
    <FILENAME>cbu-20240515_lab.xml
    <DESCRIPTION>INLINE XBRL TAXONOMY EXTENSION - LABEL LINKBASE
    <TEXT>
    Document 4 - file: cbu-20240515_lab.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.PRE
    <SEQUENCE>5
    <FILENAME>cbu-20240515_pre.xml
    <DESCRIPTION>INLINE XBRL TAXONOMY EXTENSION - PRESENTATION LINKBASE
    <TEXT>
    Document 5 - file: cbu-20240515_pre.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>6
    <FILENAME>logo_communitybank2022.jpg
    <TEXT>
    Document 6 - file: logo_communitybank2022.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>7
    <FILENAME>logo_communitybank2022x1.jpg
    <TEXT>
    Document 7 - file: logo_communitybank2022x1.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>8
    <FILENAME>logo_communitybank2022x2.jpg
    <TEXT>
    Document 8 - file: logo_communitybank2022x2.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>9
    <FILENAME>logo_communitybankft2022.jpg
    <TEXT>
    Document 9 - file: logo_communitybankft2022.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>10
    <FILENAME>ny20001814x999_checkmark.jpg
    <TEXT>
    Document 10 - file: ny20001814x999_checkmark.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>11
    <FILENAME>ny20001814x999_checkmarx1.jpg
    <TEXT>
    Document 11 - file: ny20001814x999_checkmarx1.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>12
    <FILENAME>ny20001814x999_xmark.jpg
    <TEXT>
    Document 12 - file: ny20001814x999_xmark.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>13
    <FILENAME>ny20019223x1_bace.jpg
    <TEXT>
    Document 13 - file: ny20019223x1_bace.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>14
    <FILENAME>ny20019223x1_charts1x1.jpg
    <TEXT>
    Document 14 - file: ny20019223x1_charts1x1.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>15
    <FILENAME>ny20019223x1_charts2x2.jpg
    <TEXT>
    Document 15 - file: ny20019223x1_charts2x2.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>16
    <FILENAME>ny20019223x1_checkmark.jpg
    <TEXT>
    Document 16 - file: ny20019223x1_checkmark.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>17
    <FILENAME>ny20019223x1_cov.jpg
    <TEXT>
    Document 17 - file: ny20019223x1_cov.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>18
    <FILENAME>ny20019223x1_dkaraivanov.jpg
    <TEXT>
    Document 18 - file: ny20019223x1_dkaraivanov.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>19
    <FILENAME>ny20019223x1_estickels.jpg
    <TEXT>
    Document 19 - file: ny20019223x1_estickels.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>20
    <FILENAME>ny20019223x1_jknauss.jpg
    <TEXT>
    Document 20 - file: ny20019223x1_jknauss.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>21
    <FILENAME>ny20019223x1_jparente.jpg
    <TEXT>
    Document 21 - file: ny20019223x1_jparente.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>22
    <FILENAME>ny20019223x1_jwhipple.jpg
    <TEXT>
    Document 22 - file: ny20019223x1_jwhipple.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>23
    <FILENAME>ny20019223x1_kmacpherson.jpg
    <TEXT>
    Document 23 - file: ny20019223x1_kmacpherson.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>24
    <FILENAME>ny20019223x1_mbolus.jpg
    <TEXT>
    Document 24 - file: ny20019223x1_mbolus.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>25
    <FILENAME>ny20019223x1_msullivan.jpg
    <TEXT>
    Document 25 - file: ny20019223x1_msullivan.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>26
    <FILENAME>ny20019223x1_mtryniski.jpg
    <TEXT>
    Document 26 - file: ny20019223x1_mtryniski.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>27
    <FILENAME>ny20019223x1_nfesette.jpg
    <TEXT>
    Document 27 - file: ny20019223x1_nfesette.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>28
    <FILENAME>ny20019223x1_piechart1.jpg
    <TEXT>
    Document 28 - file: ny20019223x1_piechart1.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>29
    <FILENAME>ny20019223x1_piechart2.jpg
    <TEXT>
    Document 29 - file: ny20019223x1_piechart2.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>30
    <FILENAME>ny20019223x1_pvpchart01.jpg
    <TEXT>
    Document 30 - file: ny20019223x1_pvpchart01.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>31
    <FILENAME>ny20019223x1_pvpchart02.jpg
    <TEXT>
    Document 31 - file: ny20019223x1_pvpchart02.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>32
    <FILENAME>ny20019223x1_pvpchart03.jpg
    <TEXT>
    Document 32 - file: ny20019223x1_pvpchart03.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>33
    <FILENAME>ny20019223x1_pvpchart04.jpg
    <TEXT>
    Document 33 - file: ny20019223x1_pvpchart04.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>34
    <FILENAME>ny20019223x1_rpecor.jpg
    <TEXT>
    Document 34 - file: ny20019223x1_rpecor.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>35
    <FILENAME>ny20019223x1_sskerritt.jpg
    <TEXT>
    Document 35 - file: ny20019223x1_sskerritt.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>36
    <FILENAME>ny20019223x1_ssteele.jpg
    <TEXT>
    Document 36 - file: ny20019223x1_ssteele.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>37
    <FILENAME>ny20019223x1_table2x1.jpg
    <TEXT>
    Document 37 - file: ny20019223x1_table2x1.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>38
    <FILENAME>ny20019223x1_xmark.jpg
    <TEXT>
    Document 38 - file: ny20019223x1_xmark.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>39
    <FILENAME>sig_dcima.jpg
    <TEXT>
    Document 39 - file: sig_dcima.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>40
    <FILENAME>sig_dkaraivanov.jpg
    <TEXT>
    Document 40 - file: sig_dkaraivanov.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>41
    <FILENAME>sig_ericstickels.jpg
    <TEXT>
    Document 41 - file: sig_ericstickels.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>42
    <FILENAME>ny20019223x1_chair.jpg
    <TEXT>
    Document 42 - file: ny20019223x1_chair.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>43
    <FILENAME>ny20019223x1_member.jpg
    <TEXT>
    Document 43 - file: ny20019223x1_member.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>44
    <FILENAME>ny20019223x1_pc01.jpg
    <TEXT>
    Document 44 - file: ny20019223x1_pc01.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>45
    <FILENAME>ny20019223x1_pc02.jpg
    <TEXT>
    Document 45 - file: ny20019223x1_pc02.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>47
    <FILENAME>R1.htm
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 47 - file: R1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>48
    <FILENAME>R2.htm
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 48 - file: R2.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>49
    <FILENAME>Show.js
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 49 - file: Show.js

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>50
    <FILENAME>report.css
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 50 - file: report.css

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>52
    <FILENAME>FilingSummary.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 52 - file: FilingSummary.html

    Document 52 - RAW XML: FilingSummary.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>JSON
    <SEQUENCE>54
    <FILENAME>MetaLinks.json
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 54 - file: MetaLinks.json

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>ZIP
    <SEQUENCE>55
    <FILENAME>0001140361-24-016502-xbrl.zip
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 55 - file: 0001140361-24-016502-xbrl.zip

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>57
    <FILENAME>ny20019223x1_def14a_htm.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 57 - file: ny20019223x1_def14a_htm.html

    Document 57 - RAW XML: ny20019223x1_def14a_htm.xml

    </DOCUMENT>
    </SEC-DOCUMENT>