Revenue Recognition - Summary of Estimated Revenue Related to Performance Obligations (Detail) $ in Millions	May 31, 2020 USD ($)
Railcar sales
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue type 1	$ 400.0
Services
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue type 1	134.8
Other
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue type 1	132.3
Manufacturing | Railcar sales
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue type 1	2,292.1
Manufacturing | Marine
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue type 1	36.8
Manufacturing | Railcars for Syndication
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue type 1	$ 239.1	[1]

[1] Not a performance obligation as defined in Topic 606