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
	Mar. 31, 2015	Mar. 31, 2014
Share-Based Compensation and Capital Stock [Line Items]
Pretax share-based compensation expense	$ 2.8	$ 3.0
Income tax benefits	1.0	1.1
Stock Options [Member]
Share-Based Compensation and Capital Stock [Line Items]
Pretax share-based compensation expense	0.7	0.4
Restricted Stock [Member]
Share-Based Compensation and Capital Stock [Line Items]
Pretax share-based compensation expense	1.8	1.9
Performance Vested Restricted Stock Units [Member]
Share-Based Compensation and Capital Stock [Line Items]
Pretax share-based compensation expense	$ 0.3	$ 0.7