Share-Based Compensation and Capital Stock Pre-Tax Stock-Based Compensation Expenses And Associated Income Tax Benefits (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Share-Based Compensation and Capital Stock [Line Items]
Pretax share-based compensation expense	$ 2.9	$ 1.8	$ 5.7	$ 4.8
Income tax benefits	1.1	0.7	2.1	1.8
Stock Options [Member]
Share-Based Compensation and Capital Stock [Line Items]
Pretax share-based compensation expense	0.9	0.7	1.6	1.1
Restricted Stock [Member]
Share-Based Compensation and Capital Stock [Line Items]
Pretax share-based compensation expense	1.7	1.9	3.5	3.8
Performance Vested Restricted Stock Units [Member]
Share-Based Compensation and Capital Stock [Line Items]
Pretax share-based compensation expense	$ 0.3	$ (0.8)	$ 0.6	$ (0.1)