Stock-Based Compensation (Stock Option Activity) (Details) - Stock Options $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2016 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, outstanding, beginning of period (in shares) | shares	504,462
Options, granted (in shares) | shares	255,825
Options, exercised (in shares) | shares	(36,088)
Options, outstanding, end of period (in shares) | shares	724,199
Options, vested and expected to vest (in shares) | shares	668,490
Options, exercisable (in shares) | shares	361,851
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) | $ / shares	$ 69.99
Weighted average exercise price, granted (per share) | $ / shares	90.90
Weighted average exercise price, exercised (per share) | $ / shares	24.39
Weighted average exercise price, end of period (per share) | $ / shares	79.65
Weighted average exercise price, vested and expected to vest (per share) | $ / shares	78.46
Weighted average exercise price, exercisable (per share) | $ / shares	$ 64.98
Weighted average remaining contractual term (in years)	7 years 7 months 10 days
Weighted average remaining contractual term, vested and expected to vest (in years)	7 years 5 months 16 days
Weighted average remaining contractual term, exercisable (in years)	5 years 11 months 8 days
Options, outstanding, intrinsic value | $	$ 8.4
Options, vested and expected to vest, intrinsic value | $	8.4
Options, vested and expected to vest, exercisable | $	$ 8.3