Share-Based Compensation and Capital Stock Pre-Tax Stock-Based Compensation Expenses And Associated Income Tax Benefits (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Share-Based Compensation and Capital Stock [Line Items]
Pretax share-based compensation expense	$ 3.4	$ 3.1	$ 9.1	$ 7.9
Income tax benefits	1.3	1.1	3.4	2.9
Stock Options [Member]
Share-Based Compensation and Capital Stock [Line Items]
Pretax share-based compensation expense	0.8	0.6	2.4	1.7
Restricted Stock [Member]
Share-Based Compensation and Capital Stock [Line Items]
Pretax share-based compensation expense	1.6	1.7	5.1	5.5
Performance Vested Restricted Stock Units [Member]
Share-Based Compensation and Capital Stock [Line Items]
Pretax share-based compensation expense	$ 1.0	$ 0.8	$ 1.6	$ 0.7