Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Millions, $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 54.2	$ 59.5
Common stock, par value	$ 0.10	$ 0.10
Common stock, shares authorized	800.0	800.0
Common stock, shares issued	406.3	414.6
Common stock, shares outstanding	403.2	413.8
Treasury stock, shares	3.1	0.8