Segment Information - Additional Information (Detail)	Aug. 20, 2018 Segment Facility	Aug. 19, 2018 Segment
Segment Reporting Information [Line Items]
Number of reportable segments \| Segment	3	4
Number of railcars repair shops returned to business \| Facility	12

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

No definition available.

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration