Stock-Based Compensation (Stock Option Activity) (Details) - Jun. 30, 2015 - Stock Options - USD ($) $ / shares in Units, $ in Millions	Total
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, outstanding, beginning of period (in shares)	618,115
Options, granted (in shares)	133,814
Options, exercised (in shares)	(197,591)
Options, forfeited (in shares)	(14,348)
Options, outstanding, end of period (in shares)	539,990
Options, vested and expected to vest (in shares)	507,678
Options, exercisable (in shares)	324,927
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)	$ 53.10
Weighted average exercise price, granted (per share)	111.54
Weighted average exercise price, exercised (per share)	42.38
Weighted average exercise price, forfeited (per share)	96.83
Weighted average exercise price, end of period (per share)	70.35
Weighted average exercise price, vested and expected to vest (per share)	68.37
Weighted average exercise price, exercisable (per share)	$ 51.87
Weighted average remaining contractual term (in years)	7 years 4 months 9 days
Weighted average remaining contractual term, vested and expected to vest (in years)	7 years 2 months 24 days
Weighted average remaining contractual term, exercisable (in years)	6 years 1 month 25 days
Options, outstanding, intrinsic value	$ 17.1
Options, vested and expected to vest, intrinsic value	16.9
Options, vested and expected to vest, exercisable	$ 15.3