Share-Based Compensation and Capital Stock Pre-Tax Stock-Based Compensation Expenses And Associated Income Tax Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Pre-tax stock-based compensation expenses	$ 2.9	$ 3.1	$ 8.7	$ 8.6
Income tax benefits	1.1	1.1	3.2	3.2
Stock Options [Member]
Pre-tax stock-based compensation expenses	0.3	0.5	1.3	1.6
Restricted Stock [Member]
Pre-tax stock-based compensation expenses	2.1	1.8	5.7	5.7
Performance Vested Restricted Stock Units [Member]
Pre-tax stock-based compensation expenses	$ 0.5	$ 0.8	$ 1.7	$ 1.3