Business Segments (Reconciliation of Assets from Segment to Consolidated) (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Segment Reporting Information
Assets	$ 387,644	$ 396,556
Operating Segments \| Rail Products and Services
Segment Reporting Information
Assets	183,072	192,038
Operating Segments \| Construction Products
Segment Reporting Information
Assets	85,477	83,154
Operating Segments \| Tubular and Energy Services
Segment Reporting Information
Assets	96,186	100,706
Unallocated corporate assets
Segment Reporting Information
Assets	$ 22,909	$ 20,658

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(12))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(11))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Name:	us-gaap_Assets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant