Inventories - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Percentage of inventories valued on the LIFO method	35.00%	36.00%
The LIFO reserve approximated	$ (17,321)	$ (26,058)
The LIFO reserve of the Avonmore Plant approximated		5,240
Income tax expense recognized related to liquidation	0	0
Decrease in costs of products sold	467	2,159
Net income	$ 467	$ 2,159
Common per share	$ 0.04	$ 0.17