Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Allowance for doubtful accounts	$ 16.1	$ 11.7
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	2,000,000,000	2,000,000,000
Common stock, shares issued (in shares)	544,003,038	544,003,038
Common stock, shares outstanding (in shares)	162,751,449	163,161,564
Treasury stock, shares (in shares)	381,251,589	380,841,474