Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Accounts and notes receivable, allowances	$ 22.6	$ 25.6
Common stock, par value (per share)	$ 0.01	$ 0.01
Common stock, shares authorized	426,000,000	426,000,000
Common stock, shares issued	180,300,000	181,800,000