    <SEC-DOCUMENT>0000040211-23-000062-index.html : 20230511
    <SEC-HEADER>0000040211-23-000062.hdr.sgml : 20230511
    <ACCEPTANCE-DATETIME>20230511110432
    ACCESSION NUMBER:		0000040211-23-000062
    CONFORMED SUBMISSION TYPE:	8-K
    PUBLIC DOCUMENT COUNT:		80
    CONFORMED PERIOD OF REPORT:	20230511
    ITEM INFORMATION:		Regulation FD Disclosure
    ITEM INFORMATION:		Financial Statements and Exhibits
    FILED AS OF DATE:		20230511
    DATE AS OF CHANGE:		20230511

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			GATX CORP
    		CENTRAL INDEX KEY:			0000040211
    		STANDARD INDUSTRIAL CLASSIFICATION:	TRANSPORTATION SERVICES [4700]
    		IRS NUMBER:				361124040
    		STATE OF INCORPORATION:			NY
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		8-K
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	001-02328
    		FILM NUMBER:		23909626

    	BUSINESS ADDRESS:
    		STREET 1:		233 SOUTH WACKER DRIVE
    		CITY:			CHICAGO
    		STATE:			IL
    		ZIP:			60606-7147
    		BUSINESS PHONE:		3126216200

    	MAIL ADDRESS:
    		STREET 1:		233 SOUTH WACKER DRIVE
    		CITY:			CHICAGO
    		STATE:			IL
    		ZIP:			60606-7147

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	GENERAL AMERICAN TRANSPORTATION CORP
    		DATE OF NAME CHANGE:	19750722
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>8-K
    <SEQUENCE>1
    <FILENAME>gatx-20230511.htm
    <DESCRIPTION>8-K
    <TEXT>
    Document 1 - file: gatx-20230511.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.1
    <SEQUENCE>2
    <FILENAME>a2023companyoverview-fin.htm
    <DESCRIPTION>EX-99.1
    <TEXT>
    Document 2 - file: a2023companyoverview-fin.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.SCH
    <SEQUENCE>3
    <FILENAME>gatx-20230511.xsd
    <DESCRIPTION>XBRL TAXONOMY EXTENSION SCHEMA DOCUMENT
    <TEXT>
    Document 3 - file: gatx-20230511.xsd

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.DEF
    <SEQUENCE>4
    <FILENAME>gatx-20230511_def.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION DEFINITION LINKBASE DOCUMENT
    <TEXT>
    Document 4 - file: gatx-20230511_def.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.LAB
    <SEQUENCE>5
    <FILENAME>gatx-20230511_lab.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION LABEL LINKBASE DOCUMENT
    <TEXT>
    Document 5 - file: gatx-20230511_lab.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.PRE
    <SEQUENCE>6
    <FILENAME>gatx-20230511_pre.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE DOCUMENT
    <TEXT>
    Document 6 - file: gatx-20230511_pre.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>7
    <FILENAME>a2023companyoverview-fin001.jpg
    <TEXT>
    Document 7 - file: a2023companyoverview-fin001.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>8
    <FILENAME>a2023companyoverview-fin002.jpg
    <TEXT>
    Document 8 - file: a2023companyoverview-fin002.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>9
    <FILENAME>a2023companyoverview-fin003.jpg
    <TEXT>
    Document 9 - file: a2023companyoverview-fin003.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>10
    <FILENAME>a2023companyoverview-fin004.jpg
    <TEXT>
    Document 10 - file: a2023companyoverview-fin004.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>11
    <FILENAME>a2023companyoverview-fin005.jpg
    <TEXT>
    Document 11 - file: a2023companyoverview-fin005.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>12
    <FILENAME>a2023companyoverview-fin006.jpg
    <TEXT>
    Document 12 - file: a2023companyoverview-fin006.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>13
    <FILENAME>a2023companyoverview-fin007.jpg
    <TEXT>
    Document 13 - file: a2023companyoverview-fin007.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>14
    <FILENAME>a2023companyoverview-fin008.jpg
    <TEXT>
    Document 14 - file: a2023companyoverview-fin008.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>15
    <FILENAME>a2023companyoverview-fin009.jpg
    <TEXT>
    Document 15 - file: a2023companyoverview-fin009.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>16
    <FILENAME>a2023companyoverview-fin010.jpg
    <TEXT>
    Document 16 - file: a2023companyoverview-fin010.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>17
    <FILENAME>a2023companyoverview-fin011.jpg
    <TEXT>
    Document 17 - file: a2023companyoverview-fin011.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>18
    <FILENAME>a2023companyoverview-fin012.jpg
    <TEXT>
    Document 18 - file: a2023companyoverview-fin012.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>19
    <FILENAME>a2023companyoverview-fin013.jpg
    <TEXT>
    Document 19 - file: a2023companyoverview-fin013.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>20
    <FILENAME>a2023companyoverview-fin014.jpg
    <TEXT>
    Document 20 - file: a2023companyoverview-fin014.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>21
    <FILENAME>a2023companyoverview-fin015.jpg
    <TEXT>
    Document 21 - file: a2023companyoverview-fin015.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>22
    <FILENAME>a2023companyoverview-fin016.jpg
    <TEXT>
    Document 22 - file: a2023companyoverview-fin016.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>23
    <FILENAME>a2023companyoverview-fin017.jpg
    <TEXT>
    Document 23 - file: a2023companyoverview-fin017.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>24
    <FILENAME>a2023companyoverview-fin018.jpg
    <TEXT>
    Document 24 - file: a2023companyoverview-fin018.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>25
    <FILENAME>a2023companyoverview-fin019.jpg
    <TEXT>
    Document 25 - file: a2023companyoverview-fin019.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>26
    <FILENAME>a2023companyoverview-fin020.jpg
    <TEXT>
    Document 26 - file: a2023companyoverview-fin020.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>27
    <FILENAME>a2023companyoverview-fin021.jpg
    <TEXT>
    Document 27 - file: a2023companyoverview-fin021.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>28
    <FILENAME>a2023companyoverview-fin022.jpg
    <TEXT>
    Document 28 - file: a2023companyoverview-fin022.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>29
    <FILENAME>a2023companyoverview-fin023.jpg
    <TEXT>
    Document 29 - file: a2023companyoverview-fin023.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>30
    <FILENAME>a2023companyoverview-fin024.jpg
    <TEXT>
    Document 30 - file: a2023companyoverview-fin024.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>31
    <FILENAME>a2023companyoverview-fin025.jpg
    <TEXT>
    Document 31 - file: a2023companyoverview-fin025.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>32
    <FILENAME>a2023companyoverview-fin026.jpg
    <TEXT>
    Document 32 - file: a2023companyoverview-fin026.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>33
    <FILENAME>a2023companyoverview-fin027.jpg
    <TEXT>
    Document 33 - file: a2023companyoverview-fin027.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>34
    <FILENAME>a2023companyoverview-fin028.jpg
    <TEXT>
    Document 34 - file: a2023companyoverview-fin028.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>35
    <FILENAME>a2023companyoverview-fin029.jpg
    <TEXT>
    Document 35 - file: a2023companyoverview-fin029.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>36
    <FILENAME>a2023companyoverview-fin030.jpg
    <TEXT>
    Document 36 - file: a2023companyoverview-fin030.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>37
    <FILENAME>a2023companyoverview-fin031.jpg
    <TEXT>
    Document 37 - file: a2023companyoverview-fin031.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>38
    <FILENAME>a2023companyoverview-fin032.jpg
    <TEXT>
    Document 38 - file: a2023companyoverview-fin032.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>39
    <FILENAME>a2023companyoverview-fin033.jpg
    <TEXT>
    Document 39 - file: a2023companyoverview-fin033.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>40
    <FILENAME>a2023companyoverview-fin034.jpg
    <TEXT>
    Document 40 - file: a2023companyoverview-fin034.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>41
    <FILENAME>a2023companyoverview-fin035.jpg
    <TEXT>
    Document 41 - file: a2023companyoverview-fin035.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>42
    <FILENAME>a2023companyoverview-fin036.jpg
    <TEXT>
    Document 42 - file: a2023companyoverview-fin036.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>43
    <FILENAME>a2023companyoverview-fin037.jpg
    <TEXT>
    Document 43 - file: a2023companyoverview-fin037.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>44
    <FILENAME>a2023companyoverview-fin038.jpg
    <TEXT>
    Document 44 - file: a2023companyoverview-fin038.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>45
    <FILENAME>a2023companyoverview-fin039.jpg
    <TEXT>
    Document 45 - file: a2023companyoverview-fin039.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>46
    <FILENAME>a2023companyoverview-fin040.jpg
    <TEXT>
    Document 46 - file: a2023companyoverview-fin040.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>47
    <FILENAME>a2023companyoverview-fin041.jpg
    <TEXT>
    Document 47 - file: a2023companyoverview-fin041.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>48
    <FILENAME>a2023companyoverview-fin042.jpg
    <TEXT>
    Document 48 - file: a2023companyoverview-fin042.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>49
    <FILENAME>a2023companyoverview-fin043.jpg
    <TEXT>
    Document 49 - file: a2023companyoverview-fin043.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>50
    <FILENAME>a2023companyoverview-fin044.jpg
    <TEXT>
    Document 50 - file: a2023companyoverview-fin044.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>51
    <FILENAME>a2023companyoverview-fin045.jpg
    <TEXT>
    Document 51 - file: a2023companyoverview-fin045.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>52
    <FILENAME>a2023companyoverview-fin046.jpg
    <TEXT>
    Document 52 - file: a2023companyoverview-fin046.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>53
    <FILENAME>a2023companyoverview-fin047.jpg
    <TEXT>
    Document 53 - file: a2023companyoverview-fin047.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>54
    <FILENAME>a2023companyoverview-fin048.jpg
    <TEXT>
    Document 54 - file: a2023companyoverview-fin048.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>55
    <FILENAME>a2023companyoverview-fin049.jpg
    <TEXT>
    Document 55 - file: a2023companyoverview-fin049.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>56
    <FILENAME>a2023companyoverview-fin050.jpg
    <TEXT>
    Document 56 - file: a2023companyoverview-fin050.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>57
    <FILENAME>a2023companyoverview-fin051.jpg
    <TEXT>
    Document 57 - file: a2023companyoverview-fin051.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>58
    <FILENAME>a2023companyoverview-fin052.jpg
    <TEXT>
    Document 58 - file: a2023companyoverview-fin052.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>59
    <FILENAME>a2023companyoverview-fin053.jpg
    <TEXT>
    Document 59 - file: a2023companyoverview-fin053.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>60
    <FILENAME>a2023companyoverview-fin054.jpg
    <TEXT>
    Document 60 - file: a2023companyoverview-fin054.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>61
    <FILENAME>a2023companyoverview-fin055.jpg
    <TEXT>
    Document 61 - file: a2023companyoverview-fin055.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>62
    <FILENAME>a2023companyoverview-fin056.jpg
    <TEXT>
    Document 62 - file: a2023companyoverview-fin056.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>63
    <FILENAME>a2023companyoverview-fin057.jpg
    <TEXT>
    Document 63 - file: a2023companyoverview-fin057.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>64
    <FILENAME>a2023companyoverview-fin058.jpg
    <TEXT>
    Document 64 - file: a2023companyoverview-fin058.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>65
    <FILENAME>a2023companyoverview-fin059.jpg
    <TEXT>
    Document 65 - file: a2023companyoverview-fin059.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>66
    <FILENAME>a2023companyoverview-fin060.jpg
    <TEXT>
    Document 66 - file: a2023companyoverview-fin060.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>67
    <FILENAME>a2023companyoverview-fin061.jpg
    <TEXT>
    Document 67 - file: a2023companyoverview-fin061.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>68
    <FILENAME>a2023companyoverview-fin062.jpg
    <TEXT>
    Document 68 - file: a2023companyoverview-fin062.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>69
    <FILENAME>a2023companyoverview-fin063.jpg
    <TEXT>
    Document 69 - file: a2023companyoverview-fin063.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>70
    <FILENAME>a2023companyoverview-fin064.jpg
    <TEXT>
    Document 70 - file: a2023companyoverview-fin064.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>71
    <FILENAME>a2023companyoverview-fin065.jpg
    <TEXT>
    Document 71 - file: a2023companyoverview-fin065.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>72
    <FILENAME>a2023companyoverview-fin066.jpg
    <TEXT>
    Document 72 - file: a2023companyoverview-fin066.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>73
    <FILENAME>R1.htm
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 73 - file: R1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>74
    <FILENAME>gatx-20230511_htm.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 74 - file: gatx-20230511_htm.html

    Document 74 - RAW XML: gatx-20230511_htm.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EXCEL
    <SEQUENCE>75
    <FILENAME>Financial_Report.xlsx
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 75 - file: Financial_Report.xlsx

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>76
    <FILENAME>Show.js
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 76 - file: Show.js

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>77
    <FILENAME>report.css
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 77 - file: report.css

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>78
    <FILENAME>FilingSummary.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 78 - file: FilingSummary.html

    Document 78 - RAW XML: FilingSummary.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>JSON
    <SEQUENCE>80
    <FILENAME>MetaLinks.json
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 80 - file: MetaLinks.json

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>ZIP
    <SEQUENCE>81
    <FILENAME>0000040211-23-000062-xbrl.zip
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 81 - file: 0000040211-23-000062-xbrl.zip

    </DOCUMENT>
    </SEC-DOCUMENT>