Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Per Share data	Sep. 30, 2011	Dec. 31, 2010
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 10.5	$ 11.0
Preferred shares - par value	$ 0	$ 0
Preferred shares - without par value, authorized	5.0	5.0
Preferred shares - without par value, outstanding	0	0
Common shares - par value	$ 0	$ 0
Common shares - without par value, authorized	500.0	500.0
Common shares - without par value, issued	184.9	184.2
Common shares - without par value, outstanding	120.1	122.1
Treasury stock - shares	64.8	62.1