Partially-Owned Leasing Subsidiaries - Narrative (Details) $ in Millions	6 Months Ended	24 Months Ended
Jun. 30, 2023 USD ($) board_member subsidiary	Jun. 30, 2023 USD ($) 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%
Equity Method Investment, Aggregate Future Estimated Investment of Railcars	$ 1,000.0	$ 1,000.0
Proceeds from Sales of Business, Affiliate and Productive Assets		598.6
Equity Method Investments	20.9	20.9
Partially-owned subsidiaries
Noncontrolling Interest [Line Items]
Parent Company Guarantees	$ 0.0	$ 0.0
Railcar Leasing and Management Services Group [Member] \| 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 \| Railcar Leasing and Management Services Group [Member]
Noncontrolling Interest [Line Items]
Carrying Value of Investment In Partially-Owned Consolidated Subsidiary	$ 134.1	$ 134.1
Noncontrolling Interest, Ownership Percentage by Parent	38.00%	38.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	62.00%	62.00%

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

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

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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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