Accounts Receivable, Net - Schedule of Accounts Receivable, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounts Notes And Loans Receivable [Line Items]
Allowance for doubtful accounts	$ (70)	$ (70)
Total accounts receivable, net	10,446	10,347
Security Products
Accounts Notes And Loans Receivable [Line Items]
Accounts receivable, gross	9,341	9,329
Marine Components
Accounts Notes And Loans Receivable [Line Items]
Accounts receivable, gross	$ 1,175	$ 1,088