CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
CONSOLIDATED BALANCE SHEETS
Accounts receivable, allowances (in dollars)	$ 7,851	$ 5,448
Other accounts receivable, allowances (in dollars)	$ 660	$ 476
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized shares	70,000,000	70,000,000
Common stock, issued shares	29,045,309	28,810,902
Treasury stock, at cost, shares	3,656,938	3,404,639