Inventories - Inventories (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Inventory [Line Items]
Total raw materials	$ 2,730	$ 2,743
Total work-in-process	9,836	8,988
Total finished goods	2,816	3,243
Total inventories	15,382	14,974
Security Products
Inventory [Line Items]
Total raw materials	2,156	2,365
Total work-in-process	8,290	7,387
Total finished goods	2,079	2,440
Marine Components
Inventory [Line Items]
Total raw materials	574	378
Total work-in-process	1,546	1,601
Total finished goods	$ 737	$ 803