Summary of Significant Accounting Policies Revenue Recognition and Remaining performance obligation (Details) - USD ($) $ in Millions		Sep. 30, 2022	Dec. 31, 2021
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Billed Contracts Receivable		$ 3.0	$ 4.5
Rail Products Group [Member] | Rail Products [Domain]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount		$ 4,090.9
Revenue, remaining performance obligation expected to be delivered in current year		16.20%
Rail Products Group [Member] | Rail Products [Domain] | External Customers
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	[1]	$ 3,573.7
Rail Products Group [Member] | Rail Products [Domain] | Leasing
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount		517.2
Rail Products Group [Member] | Rail Products [Domain] | GATX
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	[1]	1,800.0
Rail Products Group [Member] | Sustainable Railcar Conversions
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount		$ 201.4
Revenue, remaining performance obligation expected to be delivered in current year		26.50%
Railcar Leasing and Management Services Group [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount		$ 133.6
Revenue, remaining performance obligation expected to be delivered in current year		6.80%

[1] Unsatisfied performance obligations at September 30, 2022 include 15,000 railcars expected to be delivered through 2028, valued at approximately $1.8 billion, associated with a new long-term railcar supply agreement with GATX Corporation.