Stock-Based Compensation Plans (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014 Stock-Based Comp Plans	Mar. 31, 2013 Stock-Based Comp Plans	Mar. 31, 2014 Amended and Restated 2010 Stock Incentive Plan and 2005 Directors Stock Plan	May 17, 2005 Stock Incentive Plan, Directors Stock Plan and Long-Term Performance Plan
Stock-Based Compensation Plans - Disclosures
Number of shares that will be granted				0
Maximum number of new shares of common stock available for grant (in shares)			5,200,000
Compensation cost	$ 16.8	$ 15.6
Related income tax benefit	5.7	4.7
Capitalized as part of an asset	$ 0.7	$ 0.6