Note 6. Railcar Leasing and Management Services Group Selected Leasing Income Statement Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues	$ 850.7	$ 813.6	$ 736.0	$ 604.8	$ 735.0	$ 606.9	$ 634.0	$ 533.2	$ 3,005.1	$ 2,509.1	$ 2,397.4
Operating Income (Loss)	97.2	120.3	107.0	91.8	89.8	75.2	88.0	62.1	416.3	315.1	368.3
Depreciation, Depletion and Amortization									283.6	251.9	229.7
Operating Leases, Rent Expense									18.0
Selling, General and Administrative Expense	$ 71.3	$ 62.1	$ 69.8	$ 59.6	$ 72.0	$ 75.6	$ 75.6	$ 73.4	262.8	296.6	339.3
Interest Expense									221.8	179.3	184.0
Operating Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues									3,005.1	2,509.1	2,397.4
Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues									$ 1,117.2	$ 842.8	843.2
Revenues, Percent Change									32.60%	0.00%
Operating Income (Loss)									$ 406.6	$ 351.1	$ 444.5
Operating Income (Loss), Percent Change									15.80%	(21.00%)
Operating Profit Margin									36.40%	41.70%	52.70%
Depreciation, Depletion and Amortization									$ 232.2	$ 196.6	$ 172.3
Depreciation, Depletion, and Amortization, Percent Change									18.10%	14.10%
Cost, Maintenance									$ 102.1	$ 99.3	96.4
Maintenance Costs, Percent Change									2.80%	3.00%
Operating Leases, Rent Expense									$ 16.9	$ 42.4	39.9
Operating Leases, Rent Expense, Percent Change									(60.10%)	6.30%
Selling, General and Administrative Expense									$ 49.5	$ 51.1	50.7
Selling, Engineering, and Administrative Expense, Percent Change									(3.10%)	0.80%
Interest Expense									$ 197.2	$ 142.3	125.8
Interest Expense, Percent Change									38.60%	13.10%
Leasing and management [Member] | Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues									$ 756.5	$ 728.9	743.6
Revenues, Percent Change									3.80%	(2.00%)
Operating Income (Loss)									$ 314.7	$ 291.8	$ 341.3
Operating Income (Loss), Percent Change									7.80%	(14.50%)
Operating Profit Margin									41.60%	40.00%	45.90%
Railcar Owned One Year or Less [Member] | Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues									$ 360.7	$ 113.9	$ 99.6
Revenues, Percent Change									216.70%	14.40%
Operating Income (Loss)									$ 41.4	$ 21.5	$ 19.7
Operating Income (Loss), Percent Change									92.60%	9.10%
Operating Profit Margin									11.50%	18.90%	19.80%
Railcar Owned Greater than One Year [Member] | Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Operating Income (Loss)									$ 50.5	$ 50.4	$ 83.5
Operating Income (Loss), Percent Change									0.20%	(39.60%)
Operating Profit Margin									24.60%	21.90%	23.10%
Property Disposition Gain (Loss) [Member] | Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Operating Income (Loss)									$ 0.0	$ (12.6)	$ 0.0
Other Assets [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Sales-type Lease, Lease Income									$ 160.5