Condensed Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 16.3	$ 16.5
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares issued (in shares)	53,172,127	52,918,347
Common stock, shares outstanding (in shares)	45,175,327	44,921,547
Treasury stock, shares (in shares)	7,996,800	7,996,800