Stock-Based Compensation (Stock Option Activity) (Details) - Stock Options $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2020 USD ($) $ / shares shares
Shares
Options, outstanding, beginning of period (in shares) | shares	1,217,438
Options, granted (in shares) | shares	167,969
Options, exercised (in shares) | shares	(270,024)
Options, expired (in shares) | shares	(48,119)
Options, forfeited (in shares) | shares	(45,247)
Options, outstanding, end of period (in shares) | shares	1,022,017
Options, vested and expected to vest (in shares) | shares	983,454
Options, exercisable (in shares) | shares	423,261
Weighted Average Exercise Price
Weighted average exercise price, beginning of period (per share) | $ / shares	$ 66.43
Weighted average exercise price, granted (per share) | $ / shares	87.17
Weighted average exercise price, exercised (per share) | $ / shares	76.01
Weighted average exercise price, expired (per share) | $ / shares	112.58
Weighted average exercise price, forfeited (per share) | $ / shares	86.39
Weighted average exercise price, end of period (per share) | $ / shares	64.25
Weighted average exercise price, vested and expected to vest (per share) | $ / shares	63.99
Weighted average exercise price, exercisable (per share) | $ / shares	$ 70.54
Weighted average remaining contractual term (in years)	6 years 8 months 12 days
Weighted average remaining contractual term, vested and expected to vest (in years)	6 years 8 months 12 days
Weighted average remaining contractual term, exercisable (in years)	5 years 3 months 18 days
Options, outstanding, intrinsic value | $	$ 5.5
Options, vested and expected to vest, intrinsic value | $	5.3
Options, vested and expected to vest, exercisable | $	$ 0.4