Business Segments (Reconciliation of Assets from Segment to Consolidated) (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Assets	$ 409,164	$ 393,023
Rail Products and Services
Segment Reporting Information [Line Items]
Assets	198,761	174,049
Construction Products
Segment Reporting Information [Line Items]
Assets	88,542	81,074
Tubular and Energy Services
Segment Reporting Information [Line Items]
Assets	100,046	100,006
Unallocated corporate assets
Segment Reporting Information [Line Items]
Assets	$ 21,815	$ 37,894

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