CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Accounts receivable, allowance for doubtful accounts	$ 17.9	$ 17.4
Property, plant and equipment, accumulated depreciation	$ 256.4	$ 250.0
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	203,299,647	201,051,291
Treasury stock (in shares)	2,435,272	2,881,436