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Description of Business (Details) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2024 USD ($) | Jun. 30, 2023 USD ($) | Jun. 30, 2024 USD ($) Segment | Jun. 30, 2023 USD ($)
Schedule of Equity Method Investments [Line Items] |  |  |  |
Number of business segments | Segment |  |  | 3 |
Net gain on asset dispositions | $ 25.6 | $ 41.1 | $ 61.8 | $ 88.2
Asset Impairment Charges |  |  | 0.0 | 1.2
Portfolio Investments and Capital Additions | 442.0 | 486.6 | 820.6 | 873.6
Rail International |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |
Net gain on asset dispositions | 0.7 | 0.7 | 2.0 | 1.5
Asset Impairment Charges |  |  |  | 0.0
Portfolio Investments and Capital Additions | $ 59.6 | $ 77.3 | $ 109.5 | $ 158.4

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