Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets
Receivables, allowance for doubtful accounts	$ 8,557	$ 8,719
SHAREHOLDERS' DEFICIT
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	160,000,000	160,000,000
Common stock, shares issued	95,065,638	95,065,638
Common stock, shares outstanding	56,299,949	56,336,566
Treasury stock, shares	38,765,689	38,729,072