Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Receivables allowance	$ 5.1	$ 4.0
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, authorized shares	5,000,000	5,000,000
Preferred stock, unissued shares	5,000,000	5,000,000
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, authorized shares	200,000,000	200,000,000
Common stock, shares issued	78,661,248	78,661,248
Common stock, shares outstanding	61,763,078	64,257,182
Treasury, shares	16,714,585	14,178,801