Summary of Significant Accounting Policies Revenue Recognition and Remaining performance obligation (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Rail Products Group [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Billed Contracts Receivable	$ 4.1	$ 12.6
Rail Products Group [Member] | Rail Products [Domain]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 2,364.5
Revenue, remaining performance obligation expected to be delivered in current year	19.90%
Rail Products Group [Member] | Rail Products [Domain] | External Customers
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 1,998.9
Rail Products Group [Member] | Rail Products [Domain] | Leasing & Services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	365.6
Rail Products Group [Member] | Sustainable Railcar Conversions
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 6.5
Revenue, remaining performance obligation expected to be delivered in current year	53.80%
Leasing & Services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Billed Contracts Receivable	$ 11.8	$ 8.8
Leasing & Services | Leasing and Management [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 60.8
Revenue, remaining performance obligation expected to be delivered in current year	8.20%
Leasing & Services | Maintenance services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 6.9
Revenue, remaining performance obligation expected to be delivered in current year	100.00%