Share-Based Compensation (Summary of Stock Option Activity) (Details) (Stock Options [Member], USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock Options [Member]
Shares [Roll Forward]
Outstanding, beginning balance	1,308,573
Granted	230,300	273,200	238,319
Exercised	(18,764)		0
Expired unexercised	(36,201)
Forfeited	(26,581)
Outstanding, ending balance	1,457,327	1,308,573
Vested or expected to vest, ending balance	1,431,451
Exercisable, ending balance	1,042,314
Weighted Average Exercise Price (in dollars per share) [Roll Forward]
Outstanding, beginning balance	$ 34.81
Granted	$ 32.06
Exercised	$ 28.03
Expired unexercised	$ 38.91
Forfeited	$ 29.96
Outstanding, ending balance	$ 32.97	$ 34.81
Vested or expected to vest, ending balance	$ 33.04
Exercisable, ending balance	$ 34.30
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average remaining contractual term (years), outstanding, ending balance	5 years 5 months 9 days
Weighted average remaining contractual term (years), vested or Expected to Vest, ending balance	5 years 4 months 21 days
Weighted average remaining contractual term (years), exercisable, ending balance	4 years 2 months 16 days
Aggregate intrinsic value, outstanding, ending balance	$ 7.9
Aggregate intrinsic value, vested or expected to vest, ending balance	7.7
Aggregate intrinsic value, exercisable, ending balance	$ 4.4