Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Allowance for doubtful accounts	$ 16.5	$ 14.5
Stockholders’ equity (Note 14):
Common stock, par value per share (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)	52,918,347	52,702,551
Common stock, shares outstanding (in shares)	44,921,547	45,113,722
Treasury stock, shares (in shares)	7,996,800	7,588,829