Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Accounts and notes receivable, allowances	$ 14.0	$ 14.2
Common stock, par value (per share)	$ 0.01	$ 0.01
Common stock, shares authorized	426,000,000	426,000,000
Common stock, shares issued	171,400,000	180,300,000