CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
CONSOLIDATED BALANCE SHEETS
Accounts receivable, allowances (in dollars)	$ 15,023	$ 13,149
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	17,102,530	16,971,634
Common stock, shares outstanding	16,025,745	16,138,983
Treasury stock, shares	1,076,785	832,652