Interim Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Allowance for Doubtful Accounts Receivable, Current	$ 17,016	$ 15,549
Shareholders' equity:
Preferred stock, par value	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	10,000,000	10,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares issued	44,786,011	44,786,011
Common stock, shares outstanding	25,392,875	25,541,393
Treasury stock, shares	19,393,136	19,244,618