Railcar Leasing and Management Services Group - Selected consolidating income statement information for the Leasing Group (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Revenues:
Revenues		$ 398.8	$ 615.2
Operating profit (2):
Total operating profit		60.2	73.0
Select expense information:
Depreciation (3)		66.6	66.9
Rent		3.7	3.9
Selling, engineering, and administrative expenses		54.4	64.3
Interest		51.4	61.3
Reduced Depreciation [Member]
Select expense information:
Depreciation (3)		3.5
Operating Segments [Member]
Revenues:
Revenues		398.8	615.2
Operating profit (2):
Total operating profit		84.8	127.3
Railcar Leasing and Management Services Group [Member]
Operating profit (2):
Total operating profit		78.3	92.9
Railcar Leasing and Management Services Group [Member] | Operating Segments [Member]
Revenues:
Revenues		$ 183.5	236.3
Revenues, Percent Change		(22.30%)
Operating profit (2):
Total operating profit		$ 78.3	$ 92.9
Operating Income (Loss), Percent Change		(15.70%)
Operating Profit Margin		42.70%	39.30%
Select expense information:
Depreciation (3)	[1]	$ 54.6	$ 53.6
Depreciation, Depletion, and Amortization, Percent Change	[1]	1.90%
Maintenance and compliance	[1]	$ 25.6	25.9
Maintenance Costs, Percent Change	[1]	(1.20%)
Rent	[1]	$ 1.7	3.0
Operating Leases, Rent Expense, Percent Change	[1]	(43.30%)
Selling, engineering, and administrative expenses	[1]	$ 11.3	14.3
Selling, Engineering, and Administrative Expense, Percent Change	[1]	(21.00%)
Interest	[1]	$ 45.7	55.1
Interest Expense, Percent Change	[1]	(17.10%)
Railcar Leasing and Management Services Group [Member] | Operating Segments [Member] | Leasing and Management [Member]
Revenues:
Revenues		$ 183.5	192.0
Revenues, Percent Change		(4.40%)
Operating profit (2):
Total operating profit		$ 76.6	$ 82.5
Operating Income (Loss), Percent Change		(7.20%)
Operating Profit Margin		41.70%	43.00%
Railcar Leasing and Management Services Group [Member] | Operating Segments [Member] | Railcar Owned One Year or Less [Member]
Revenues:
Revenues	[2]	$ 0.0	$ 44.3
Revenues, Percent Change	[2]	(100.00%)
Railcar Leasing and Management Services Group [Member] | Operating Segments [Member] | Sales of Leased Railcars [Domain]
Operating profit (2):
Total operating profit	[2]	$ 1.7	$ 10.4
Operating Income (Loss), Percent Change	[2]	(83.70%)
Operating Profit Margin		9.80%	9.20%

[1] 2) Operating profit includes: depreciation; maintenance and compliance; rent; 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] (1) Beginning in the fourth quarter of 2020, we made a prospective change in the presentation of sales of railcars from the lease fleet. Therefore, all railcar sales for the three months ended March 31, 2021 are presented as a net gain or loss from the disposal of a long-term asset regardless of the age of railcar that is sold. See Note 1 for more information.