Note 6. Railcar Leasing and Management Services Group Proceeds from Sale of Railcars (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
Sale of Leased Railcars [Line Items]
Proceeds From Sale Of Property Subject To Or Available For Operating Lease									$ 566.4	$ 344.4	$ 460.3
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
Railroad Transportation Equipment Owned One Year Or Less [Member] | Railcar Leasing and Management Services Group [Member]
Sale of Leased Railcars [Line Items]
Proceeds From Sale Of Property Subject To Or Available For Operating Lease									360.7	113.9	99.6
Railroad Transportation Equipment Owned More Than One Year [Member] | Railcar Leasing and Management Services Group [Member]
Sale of Leased Railcars [Line Items]
Proceeds From Sale Of Property Subject To Or Available For Operating Lease									205.7	230.5	360.7
Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Sale of Leased Railcars [Line Items]
Operating Income (Loss)									$ 406.6	$ 351.1	$ 444.5
Operating Profit Margin									36.40%	41.70%	52.70%
Operating Segments [Member] | Railcar Owned One Year or Less [Member] | Railcar Leasing and Management Services Group [Member]
Sale of Leased Railcars [Line Items]
Operating Income (Loss)									$ 41.4	$ 21.5	$ 19.7
Operating Profit Margin									11.50%	18.90%	19.80%
Operating Segments [Member] | Railcar Owned Greater than One Year [Member] | Railcar Leasing and Management Services Group [Member]
Sale of Leased Railcars [Line Items]
Operating Income (Loss)									$ 50.5	$ 50.4	$ 83.5
Operating Profit Margin									24.60%	21.90%	23.10%
Operating Segments [Member] | Sales of Leased Railcars [Domain] | Railcar Leasing and Management Services Group [Member]
Sale of Leased Railcars [Line Items]
Operating Income (Loss)									$ 91.9	$ 71.9	$ 103.2
Operating Profit Margin									16.20%	20.90%	22.40%