CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
CONSOLIDATED BALANCE SHEETS
Accounts receivable, allowances (in dollars)	$ 6,046	$ 5,437
Other accounts receivable, allowances (in dollars)	$ 890	$ 849
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	28,450,025	28,174,424
Treasury stock, at cost, shares	2,759,919	2,565,399