Inventories - Inventories (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Inventory [Line Items]
Total raw materials	$ 3,220	$ 2,941
Total work-in-process	11,668	11,771
Total finished goods	3,449	3,636
Total inventories, net	18,337	18,348
Security Products
Inventory [Line Items]
Total raw materials	2,318	2,134
Total work-in-process	9,214	9,138
Total finished goods	2,235	2,582
Marine Components
Inventory [Line Items]
Total raw materials	902	807
Total work-in-process	2,454	2,633
Total finished goods	$ 1,214	$ 1,054