Business Segment Information - Schedule of Business Segment Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net sales:
Total net sales	$ 32,311	$ 31,176
Operating income (loss):
Total operating income	5,020	4,290
Interest income	607	837
Income before taxes	5,627	5,127
Operating Segments | Security Products
Net sales:
Total net sales	25,469	24,704
Operating income (loss):
Total operating income	5,713	5,076
Operating Segments | Marine Components
Net sales:
Total net sales	6,842	6,472
Operating income (loss):
Total operating income	1,082	901
Corporate
Operating income (loss):
Total operating income	$ (1,775)	$ (1,687)