Costs, Estimated Earnings, and Related Billings on Uncompleted Contracts - Contracts in Progress (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Contractors [Abstract]
Costs incurred on uncompleted contracts	$ 32,488	$ 26,340
Estimated earnings	6,172	1,193
Total cost and earnings of unbilled contracts	38,660	27,533
Billings on uncompleted contracts	(34,018)	(21,912)
Total Costs, estimated earnings, and related billing on uncompleted contracts	$ 4,642	$ 5,621

Amount to be collected within one year of the balance sheet date (or one operating cycle, if longer) from customers in accordance with the contractual provisions of long-term contracts or programs including amounts billed and unbilled as of the balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.3(c))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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