Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Allowance for doubtful accounts receivable	$ 18,887	$ 18,369
Accumulated depreciation of property and equipment	281,165	262,470
Accumulated amortization of intangible assets	158,286	150,347
Accumulated amortization of other assets	$ 38,464	$ 36,984
Preferred Stock, par value per share	$ 0.02	$ 0.02
Preferred Stock, shares authorized	10,000,000	10,000,000
Preferred Stock, shares issued	0	0
Common Stock, par value per share	$ 0.02	$ 0.02
Common Stock, shares authorized	90,000,000	90,000,000
Common Stock, shares issued	58,534,749	58,389,242
Treasury Stock, shares	6,106,743	6,085,841