Accounts Receivable, Net - Schedule of Accounts Receivable, Net (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Accounts Notes And Loans Receivable [Line Items]
Allowance for doubtful accounts	$ (72)	$ (70)
Total accounts receivable, net	12,673	10,446
Security Products
Accounts Notes And Loans Receivable [Line Items]
Accounts receivable, gross	10,836	9,341
Marine Components
Accounts Notes And Loans Receivable [Line Items]
Accounts receivable, gross	$ 1,909	$ 1,175