Stock-Based Compensation (Allocation of Share-based Compensation Costs) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year 6 months
Stock compensation expense	$ 18.6	$ 21.2	$ 15.5
Stock Option and Appreciation Rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	7.6	7.7	5.3
Performance-Vesting Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	6.5	6.5	6.0
Performance-Vesting Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	1.9	2.4	0.9
Performance-vesting Shares or Units Dividend Equivalents [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	0.4	0.4	0.1
Employee Stock Purchase Plan (ESPP) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	0.5	0.4	0.4
Deferred Compensation Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	$ 1.7	$ 3.8	$ 2.8