Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 7.9	$ 7.0
Preferred shares, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred shares, authorized (in shares)	100,000,000	100,000,000
Preferred shares, issued (in shares)	0	0
Preferred shares, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common shares, authorized (in shares)	1,000,000,000.0	1,000,000,000.0
Common shares, issued (in shares)	143,000,000.0	147,700,000.0
Common shares, outstanding (in shares)	143,000,000.0	147,700,000.0