Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 13.8	$ 11.7
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	2,000,000,000	2,000,000,000
Common stock, issued (in shares)	544,003,038	544,003,038
Common stock, outstanding (in shares)	162,498,132	163,161,564
Treasury stock (in shares)	381,504,906	380,841,474