Revenue Recognition - Summary of Information About the Company's Contract Balances (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017
Revenue From Contract With Customer [Abstract]
Costs in excess of billings	$ 6,581	$ 1,310	$ 10,990
Billings in excess of costs	$ 7,843	$ 7,204	$ 5,194

Amount of receivable reflecting the cost incurred on uncompleted contracts in excess of related billings.

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