Stock-Based Compensation (Stock Option Activity) (Details) (Stock Options, USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, outstanding, beginning of period (in shares)	775,059
Options, granted (in shares)	120,932
Options, exercised (in shares)	(236,692)
Options, forfeited (in shares)	(14,804)
Options, outstanding, end of period (in shares)	644,495
Options, vested and expected to vest (in shares)	618,897
Options, exercisable (in shares)	454,011
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Weighted average exercise price, beginning of period (per share)	$ 42.09
Weighted average exercise price, granted (per share)	$ 81.53
Weighted average exercise price, exercised (per share)	$ 31.23
Weighted average exercise price, forfeited (per share)	$ 68.01
Weighted average exercise price, end of period (per share)	$ 52.88
Weighted average exercise price, vested and expected to vest (per share)	$ 51.88
Weighted average exercise price, exercisable (per share)	$ 43.92
Weighted average remaining contractual term (in years)	6 years 2 months 8 days
Weighted average remaining contractual term, vested and expected to vest (in years)	6 years 1 month 11 days
Weighted average remaining contractual term, exercisable (in years)	5 years 1 month 16 days
Options, outstanding, intrinsic value	$ 18.2
Options, vested and expected to vest, intrinsic value	18.1
Options, vested and expected to vest, exercisable	$ 16.9