Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowances for doubtful accounts and sales returns	$ 9,379	$ 8,657
Preferred stock, par value per share	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	159,589,000	158,634,000
Common stock, shares outstanding	79,522,000	80,023,000
Treasury stock, shares	80,067,000	78,611,000