Share-Based Compensation (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Share-Based Compensation [Abstract]
Fair value of share-based compensation awards, granted	$ 0.3	$ 1.1	$ 18.9	$ 17.9
Unrecognized compensation expense, net of estimated forfeitures, for unvested share-based compensation awards outstanding	$ 36.2		$ 36.2
Weighted average recognition period for unrecognized compensation expense, in years			1 year 9 months 22 days