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Number of subsidiaries.

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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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Amount of gain (loss) on sale or disposal of property, plant and equipment assets, including oil and gas property and timber property.

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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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The cash inflow from the sale of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Partially-Owned Leasing Subsidiaries - Narrative (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) board_member	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) subsidiary board_member	Sep. 30, 2020 USD ($)
Noncontrolling Interest [Line Items]
Gains on dispositions of property	$ 41.6	$ 3.9	$ 65.2	$ 20.1
Revenues	$ 503.5	$ 459.4	$ 1,273.8	$ 1,583.8
Signal Rail Holdings LLC
Noncontrolling Interest [Line Items]
Equity Method Investment, Ownership Percentage	10.00%		10.00%
Equity Method Investments	$ 6.1		$ 6.1
Proceeds from Sale of Property, Plant, and Equipment	318.7
Gains on dispositions of property	32.9
Aggregate Sales Price of Equipment Sold	325.1
Revenues	2.9
Proceeds from Equity Method Investment, Distribution	$ 6.4
Equity Method Investment, JV Majority Ownership Percentage	90.00%		90.00%
Equity Method Investment, Aggregate Future Estimated Investment of Railcars	$ 1,000.0		$ 1,000.0
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	$ 139.5		$ 139.5
Noncontrolling Interest, Ownership Percentage by Parent	38.00%		38.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	62.00%		62.00%