Summary of Significant Accounting Policies Revenue Recognition and Remaining performance obligation (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Billed Contracts Receivable	$ 12.3	$ 2.9
Rail Products Group [Member] | Rail Products [Domain]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 3,598.4
Revenue, remaining performance obligation expected to be delivered in current year	17.20%
Rail Products Group [Member] | Rail Products [Domain] | External Customers
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 3,153.6
Rail Products Group [Member] | Rail Products [Domain] | Railcar Leasing and Management Services Group [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	444.8
Rail Products Group [Member] | Sustainable Railcar Conversions
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 124.4
Revenue, remaining performance obligation expected to be delivered in current year	33.50%
Rail Products Group [Member] | Maintenance services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 7.6
Revenue, remaining performance obligation expected to be delivered in current year	100.00%
Railcar Leasing and Management Services Group [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 69.5
Revenue, remaining performance obligation expected to be delivered in current year	7.10%