Railcar Leasing and Management Services Group - Selected consolidating income statement information for the Leasing Group (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2023		Jun. 30, 2022		Jun. 30, 2023	Jun. 30, 2022
Revenues:
Revenues		$ 722.4		$ 416.8		$ 1,364.1	$ 889.5
Operating profit (1):
Total operating profit		99.1		73.0		168.1	127.8
Select expense information:
Depreciation and amortization (3)						146.8	136.2
Selling, engineering, and administrative expenses		54.3		45.0		104.2	89.7
Loss on extinguishment of debt		0.0		1.5		0.0	1.5
Operating Segments [Member]
Revenues:
Revenues		722.4		416.8		1,364.1	889.5
Operating profit (1):
Total operating profit		142.2		119.2		253.0	199.8
Railcar Leasing and Management Services Group [Member] | Operating Segments [Member]
Revenues:
Revenues		223.2		195.3		426.7	378.4
Operating profit (1):
Total operating profit		$ 118.5	[1]	$ 105.5	[1]	$ 204.0	$ 185.3
Operating Income (Loss), Percent Change		12.30%				10.10%
Operating Profit Margin		53.10%		54.00%		47.80%	49.00%
Select expense information:
Depreciation and amortization (3)	[1],[2]	$ 61.1		$ 59.4		$ 123.5	$ 116.6
Depreciation, Depletion, and Amortization, Percent Change	[1],[2]	2.90%				5.90%
Maintenance and compliance	[1]	$ 35.0		27.3		$ 70.8	56.5
Maintenance Costs, Percent Change	[1]	28.20%				25.30%
Operating lease expense	[1]	$ 4.2		5.3		$ 8.5	10.3
Operating Leases, Rent Expense, Percent Change	[1]	(20.80%)				(17.50%)
Selling, engineering, and administrative expenses	[1]	$ 14.0		12.6		$ 29.7	25.4
Selling, Engineering, and Administrative Expense, Percent Change	[1]	11.10%				16.90%
Interest (4)		$ 57.0		46.0	[3]	$ 111.8	84.7	[3]
Interest Expense, Percent Change	[3]	23.90%				32.00%
Railcar Leasing and Management Services Group [Member] | Operating Segments [Member] | Sustainable Railcar Conversions
Select expense information:
Depreciation and amortization (3)		$ 0.8		3.9		$ 5.5	6.1
Railcar Leasing and Management Services Group [Member] | Operating Segments [Member] | Leasing and Management [Member]
Revenues:
Revenues		$ 223.2		195.3		$ 426.7	378.4
Revenues, Percent Change		14.30%				12.80%
Operating profit (1):
Total operating profit	[1]	$ 88.7		$ 78.6		$ 160.7	$ 146.6
Operating Income (Loss), Percent Change		12.80%				9.60%
Operating Profit Margin		39.70%		40.20%		37.70%	38.70%
Railcar Leasing and Management Services Group [Member] | Operating Segments [Member] | Sales of Leased Railcars [Domain]
Operating profit (1):
Total operating profit	[1]	$ 29.8		$ 26.9		$ 43.3	$ 38.7	[4]
Operating Profit Margin		23.10%		18.70%		23.30%	17.40%
Select expense information:
Profit recognized at sales-type lease commencement (1)	[5]	$ 0.0		$ 0.0		$ 0.0	$ 1.3

[1] Operating profit includes: depreciation; fleet operating costs, which include maintenance, compliance, freight, and storage; rent and ad valorem taxes; and selling, engineering, and administrative expenses. Amortization of deferred profit on railcars sold from the Rail Products Group to the Leasing Group is included in the operating profit of the Leasing Group, resulting in the recognition of depreciation expense based on our original manufacturing cost of the railcars. Interest expense is not a component of operating profit and includes the effect of hedges.

[2] Depreciation expense includes $0.8 million and $5.5 million for the three and six months ended June 30, 2023, respectively, related to the disposal of certain railcar components associated with our sustainable railcar conversion program. For the three and six months ended June 30, 2022, depreciation expense includes $3.9 million and $6.1 million, respectively, related to our sustainable railcar conversion program.

[3] Interest expense for the three and six months ended June 30, 2022 includes $1.5 million of loss on extinguishment of debt associated with the repayment of TRIP Railcar Co. LLC's outstanding term loan agreement.

[4] Includes $1.3 million selling profit associated with sales-type leases for the six months ended June 30, 2022.

[5] Included in gains on dispositions of property – lease portfolio sales on our Consolidated Statements of Operations.