Partially-Owned Leasing Subsidiaries - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2022 USD ($) subsidiary board_member
Signal Rail Holdings LLC
Noncontrolling Interest [Line Items]
Equity Method Investment, JV Majority Ownership Percentage	90.00%
Equity Method Investment, Ownership Percentage	10.00%
Equity Method Investment, Aggregate Future Estimated Investment of Railcars	$ 1,000.0
Equity Method Investments	6.4
Partially-owned subsidiaries
Noncontrolling Interest [Line Items]
Parent Company Guarantees	$ 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
Number of Board Members of Subsidiary, Designated by Parent | board_member	2
Partially-owned subsidiaries | Railcar Leasing and Management Services Group [Member]
Noncontrolling Interest [Line Items]
Carrying Value of Investment In Partially-Owned Consolidated Subsidiary	$ 139.8
Noncontrolling Interest, Ownership Percentage by Parent	38.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	62.00%