Railcar Leasing and Management Services Group - Selected consolidating income statement information for the Leasing Group (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2020		Sep. 30, 2019		Sep. 30, 2020		Sep. 30, 2019
Revenues:
Revenues	$ 459.4		$ 813.6		$ 1,583.8		$ 2,154.4
Sales-type lease revenues	0.0		26.3		0.0		60.5
Operating profit (2):
Total operating profit	72.9		120.3		(161.4)		319.1
Select expense information:
Depreciation (3)(4)					199.5		210.5
Rent	3.7		4.0		12.2		13.3
Selling, engineering, and administrative expenses	51.2		62.1		172.3		191.5
Interest	52.3		55.8		166.6		165.5
Leasing [Member]
Revenues:
Revenues	183.7		326.2		612.4		803.3
Select expense information:
Selling, engineering, and administrative expenses	11.7		10.7		39.0		36.2
Operating Segments [Member]
Revenues:
Revenues	459.4		813.6		1,583.8		2,154.4
Railcar Leasing and Management Services Group [Member] | Operating Segments [Member]
Revenues:
Revenues	$ 183.9		326.4		$ 613.0		803.9
Revenues, Percent Change	(43.70%)				(23.70%)
Operating profit (2):
Total operating profit	$ 89.7		$ 115.7		$ 265.5		$ 306.3
Operating Income (Loss), Percent Change	(22.50%)				(13.30%)
Operating Profit Margin	48.80%		35.40%		43.30%		38.10%
Select expense information:
Depreciation (3)(4)	$ 51.5	[1],[2]	$ 59.4		$ 159.1	[1],[2]	$ 171.6
Depreciation, Depletion, and Amortization, Percent Change	(13.30%)				(7.30%)
Maintenance and compliance	$ 18.5		24.9		$ 67.4		79.2
Maintenance Costs, Percent Change	(25.70%)				(14.90%)
Rent	$ 2.1		3.8		$ 8.1		13.6
Operating Leases, Rent Expense, Percent Change	(44.70%)				(40.40%)
Selling, engineering, and administrative expenses	$ 11.7		10.7		$ 39.0		36.2
Selling, Engineering, and Administrative Expense, Percent Change	9.30%				7.70%
Interest	$ 47.0		50.0		$ 149.2		146.4
Interest Expense, Percent Change	(6.00%)				1.90%
Railcar Leasing and Management Services Group [Member] | Operating Segments [Member] | Leasing and Management [Member]
Revenues:
Revenues	$ 183.9		190.1		$ 558.6		566.6
Revenues, Percent Change	(3.30%)				(1.40%)
Operating profit (2):
Total operating profit	$ 86.8		$ 79.8		$ 247.8		$ 234.6
Operating Income (Loss), Percent Change	8.80%				5.60%
Operating Profit Margin	47.20%		42.00%		44.40%		41.40%
Railcar Leasing and Management Services Group [Member] | Operating Segments [Member] | Railcar Owned One Year or Less [Member]
Revenues:
Revenues	$ 0.0		$ 136.3	[3]	$ 54.4		$ 237.3	[3]
Revenues, Percent Change	(100.00%)				(77.10%)
Operating profit (2):
Total operating profit	$ 0.0		$ 17.8		$ 0.4		$ 27.0
Operating Income (Loss), Percent Change	(100.00%)				(98.50%)
Operating Profit Margin	0.00%		13.10%		0.70%		11.40%
Railcar Leasing and Management Services Group [Member] | Operating Segments [Member] | Railcar Owned Greater than One Year [Member]
Operating profit (2):
Total operating profit	$ 2.9		$ 18.1		$ 17.3		$ 44.7
Operating Income (Loss), Percent Change	(84.00%)				(61.30%)
Operating Profit Margin	44.60%		24.10%		12.50%		25.50%
Service Life [Member]
Select expense information:
Depreciation (3)(4)	$ 7.7				$ 23.1
Reduced Depreciation [Member]
Select expense information:
Depreciation (3)(4)	$ 3.5

[1] As a result of the impairment of long-lived assets related to our small cube covered hopper railcars recorded in the second quarter of 2020, our quarterly depreciation expense beginning in the third quarter of 2020 has decreased by approximately $3.5 million.

[2] Effective January 1, 2020, we revised the estimated useful lives and salvage values of certain railcar types in our lease fleet. This change in estimate resulted in a decrease in depreciation expense in the three and nine months ended September 30, 2020 of approximately $7.7 million and $23.1 million, respectively. This decrease was partially offset by higher depreciation associated with growth in the lease fleet. See Note 1 of the Consolidated Financial Statements for further information.⁽⁴⁾ As a result of the impairment of long-lived assets related to our small cube covered hopper railcars recorded in the second quarter of 2020, our quarterly depreciation expense beginning in the third quarter of 2020 has decreased by approximately $3.5 million.

[3] Includes revenues associated with sales-type leases of $26.3 million and $60.5 million for the three and nine months ended September 30, 2019, respectively.