GATX Corporation Master Trust - Schedule of Net Investment Income (Details) - EBP 002 - Master Trust Balances - USD ($) |
12 Months Ended | |
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Dec. 31, 2025 |
Dec. 31, 2024 |
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| EBP, Master Trust [Line Items] | ||
| Net appreciation in fair value of investments | $ 34,373,723 | $ 34,703,767 |
| Interest and dividend income | 3,958,425 | 3,692,811 |
| Net assets available for benefits at end of year | $ 38,332,148 | $ 38,396,578 |
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- Definition Amount of increase (decrease) in net asset available for benefit from realized and unrealized gain (loss) on investment held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of increase (decrease) in net asset available for benefit from income (loss) on investment held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Includes, but is not limited to, realized and unrealized gain (loss) on investment. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of increase in net asset available for benefit from interest and dividend income on investment held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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