Segments - Additional Information (Detail)	12 Months Ended
Dec. 31, 2018 USD ($) Segment
Segment Reporting Information [Line Items]
Reportable business segments \| Segment	3
Asset and portfolio rationalization impairment charges	$ 18,838,000
Building Materials Business West Group
Segment Reporting Information [Line Items]
Asset and portfolio rationalization impairment charges	$ 18,838,000

Amount, after cash payment, of expenses associated with exit or disposal activities pursuant to an authorized plan and expenses resulting from the write-down of assets. Excludes expenses related to a business combination, a discontinued operation or an asset retirement obligation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Name:	us-gaap_RestructuringCostsAndAssetImpairmentCharges
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration