CONSOLIDATED BALANCE SHEETS CONSOLIDATED BALANCE SHEETS (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Allowance for doubtful accounts	$ 25,400	$ 24,500
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	$ 8,876	$ 9,243
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Treasury stock, shares outstanding	21,850,356	18,391,042
Common Stock
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	210,000,000	210,000,000
Common stock, shares issued	59,308,018	59,157,696
Common stock, shares outstanding	41,797,093	45,106,085
Common Class B
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	20,000,000	20,000,000
Common stock, shares issued	4,339,431	4,339,431
Common stock, shares outstanding	0	0