Business Segment Information - Schedule of Business Segment Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net sales:
Total net sales	$ 29,948	$ 27,075
Operating income (loss):
Total operating income	4,524	3,353
Interest income	335	32
Income before taxes	4,859	3,385
Operating Segments | Security Products
Net sales:
Total net sales	26,010	23,414
Operating income (loss):
Total operating income	5,691	4,471
Operating Segments | Marine Components
Net sales:
Total net sales	3,938	3,661
Operating income (loss):
Total operating income	371	334
Corporate
Operating income (loss):
Total operating income	$ (1,538)	$ (1,452)