CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
CURRENT ASSETS:
Accounts receivable, allowances for discounts and expected credit losses	$ 5,757	$ 5,375
Property, plant and equipment, accumulated depreciation	$ 250,382	$ 239,176
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 2	$ 2
Common stock, shares authorized (in shares)	30,000,000	30,000,000
Common stock, shares issued (in shares)	23,936,036	23,936,036
Treasury stock - at cost (in shares)	2,210,069	2,350,377