Summary of Significant Accounting Policies Revenue Recognition and Remaining performance obligation (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Rail Products Group [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Billed Contracts Receivable	$ 3.2	$ 12.6
Rail Products Group [Member] | Rail Products [Domain]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 2,683.2
Revenue, remaining performance obligation expected to be delivered in current year	36.00%
Rail Products Group [Member] | Rail Products [Domain] | External Customers
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 2,281.1
Rail Products Group [Member] | Rail Products [Domain] | Leasing & Services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	402.1
Rail Products Group [Member] | Sustainable Railcar Conversions
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 19.6
Revenue, remaining performance obligation expected to be delivered in current year	84.70%
Leasing & Services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Billed Contracts Receivable	$ 12.9	$ 8.8
Leasing & Services | Leasing and Management [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 64.5
Revenue, remaining performance obligation expected to be delivered in current year	15.00%
Leasing & Services | Maintenance services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 8.3
Revenue, remaining performance obligation expected to be delivered in current year	100.00%