Summary of Significant Accounting Policies Revenue Recognition and Remaining performance obligation (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract Receivable	$ 10.1	$ 10.2
Rail Group | Railcars
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 2,865.5
Revenue, remaining performance obligation expected to be delivered in current year	50.00%
Rail Group | Railcars | External Customers
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 1,892.0
Rail Group | Railcars | Leasing
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	973.5
Rail Group | Maintenance services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 70.4
Revenue, remaining performance obligation expected to be delivered in current year	78.00%
Railcar Leasing and Management Services Group
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 100.1
Revenue, remaining performance obligation expected to be delivered in current year	12.00%