Partially-Owned Subsidiaries - Narrative (Details) $ in Millions	3 Months Ended	33 Months Ended
Mar. 31, 2024 USD ($) board_member subsidiary	Mar. 31, 2024 USD ($) board_member
Signal Rail Holdings LLC
Noncontrolling Interest [Line Items]
Equity Method Investment, JV Majority Ownership Percentage	87.10%	87.10%
Equity Method Investment, Ownership Percentage	12.90%	12.90%
Proceeds from Sales of Business, Affiliate and Productive Assets		$ 598.6
Equity Method Investments	$ 20.3	20.3
Partially-owned subsidiaries
Noncontrolling Interest [Line Items]
Parent Company Guarantees	$ 0.0	$ 0.0
Leasing & Services \| Partially-owned subsidiaries
Noncontrolling Interest [Line Items]
Number of Subsidiaries \| subsidiary	2
Number of Board Members \| board_member	7	7
Number of Board Members of Subsidiary, Designated by Parent \| board_member	2	2
Partially-owned subsidiaries \| Leasing & Services
Noncontrolling Interest [Line Items]
Carrying Value of Investment In Partially-Owned Consolidated Subsidiary	$ 124.2	$ 124.2
Noncontrolling Interest, Ownership Percentage by Parent	38.00%	38.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	62.00%	62.00%
Partially-owned subsidiaries \| Rail Products Group [Member]
Noncontrolling Interest [Line Items]
Carrying Value of Investment In Partially-Owned Consolidated Subsidiary	$ 2.5	$ 2.5
Noncontrolling Interest, Ownership Percentage by Parent	51.00%	51.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	49.00%	49.00%

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Equity Method Investment, Joint Venture Majority Ownership Percentage

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Number of subsidiaries.

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Number of Board Members

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Parent Company Guarantees

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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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-URI https://asc.fasb.org//1943274/2147481687/323-10-50-3

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481664/323-10-45-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481687/323-10-50-3

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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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.

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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

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Aggregate cash proceeds received from a combination of transactions in which noncurrent assets are sold, which may include the sale of a business, an investment in an affiliate (including an equity method investee), property, plant and equipment and intangible assets. Excludes sales of trading, available-for-sale, and held-to-maturity securities.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Accounting Standards Codification
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