Summary of Significant Accounting Policies Revenue Recognition and Remaining performance obligation (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract Receivable	$ 9.3	$ 5.2
Rail Group | Railcars
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 1,557.8
Revenue, remaining performance obligation expected to be delivered in current year	53.00%
Rail Group | Railcars | External Customers
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 976.1
Rail Group | Railcars | Leasing
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	581.7
Rail Group | Maintenance services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 20.0
Revenue, remaining performance obligation expected to be delivered in current year	92.00%
Railcar Leasing and Management Services Group
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 102.4
Revenue, remaining performance obligation expected to be delivered in current year	12.00%