Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Allowance for doubtful accounts	$ 14.5	$ 8.3
Stockholders’ equity (Note 15):
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)	52,702,551	52,524,853
Common stock, shares outstanding (in shares)	45,113,722	45,703,705
Treasury stock, shares (in shares)	7,588,829	6,821,148