Stock-Based Compensation (Stock Option Activity) (Details) - Stock Options $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, outstanding, beginning of period (in shares) | shares	701,134
Options, granted (in shares) | shares	537,030
Options, exercised (in shares) | shares	(34,916)
Options, forfeited (in shares) | shares	(23,675)
Options, outstanding, end of period (in shares) | shares	1,179,573
Options, vested and expected to vest (in shares) | shares	1,059,576
Options, exercisable (in shares) | shares	539,091
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	$ 80.04
Weighted average exercise price, granted (per share) | $ / shares	53.42
Weighted average exercise price, exercised (per share) | $ / shares	42.22
Weighted average exercise price, forfeited (per share) | $ / shares	93.97
Weighted average exercise price, end of period (per share) | $ / shares	68.76
Weighted average exercise price, vested and expected to vest (per share) | $ / shares	69.98
Weighted average exercise price, exercisable (per share) | $ / shares	$ 79.16
Weighted average remaining contractual term (in years)	6 years 8 months 7 days
Weighted average remaining contractual term, vested and expected to vest (in years)	6 years 4 months 28 days
Weighted average remaining contractual term, exercisable (in years)	3 years 6 months 1 day
Options, outstanding, intrinsic value | $	$ 1.2
Options, vested and expected to vest, intrinsic value | $	1.1
Options, vested and expected to vest, exercisable | $	$ 0.7