Inventories - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Inventory Disclosure [Abstract]
Percentage of inventories valued on the LIFO method	42.00%	45.00%
The LIFO reserve approximated	$ (16,063)	$ (15,139)
Income tax expense recognized related to liquidation	0	0
Decrease in costs of products sold	490	936	$ 216
Net income	$ 490	$ 936	$ 141
Common per share	$ 0.04	$ 0.08	$ 0.01