CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Accounts receivable, allowances	$ 2.9	$ 2.1
Preferred Stock, par value	$ 1.00	$ 1.00
Preferred Stock, Authorized	2,500,000	2,500,000
Preferred Stock, issued	0	0
Common Stock, par value	$ 1.00	$ 1.00
Common Stock, Authorized	600,000,000	300,000,000
Common Stock, shares issued	292,855,100
Common stock in treasury, shares	45,225,202	38,892,165