Stock-Based Compensation - Stock Option Activity (Details) - Stock options	9 Months Ended
	Sep. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2019 USD ($)
Stock options, Shares Subject to Options
Outstanding at the beginning of the period (in shares) | shares	1,988,696
Granted (in shares) | shares	125,794
Exercised (in shares) | shares	(117,611)
Forfeited /Expired (in shares) | shares	(14,302)
Outstanding at the end of the period (in shares) | shares	1,982,577
Exercisable at the end of the period (in shares) | shares	1,518,484
Exercisable and expected to vest at the end of the period (in shares) | shares	1,938,555
Stock options, Weighted Average Option Price
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 23.43
Granted (in dollars per share) | $ / shares	45.54
Exercised (in dollars per share) | $ / shares	20.91
Forfeited (in dollars per share) | $ / shares	20.98
Outstanding at the end of the period (in dollars per share) | $ / shares	24.96
Exercisable at the end of the period (in dollars per share) | $ / shares	21.88
Exercisable and expected to vest at the end of the period (in dollars per share) | $ / shares	$ 24.56
Stock options, additional information
Weighted Average Remaining Contractual Term, Outstanding	4 years 6 months
Weighted Average Remaining Contractual Term, Exercisable	4 years 1 month 6 days
Weighted Average Remaining Contractual Term, Exercisable and expected to vest	4 years 4 months 24 days
Aggregate Intrinsic Value, Outstanding | $	$ 30.5
Aggregate Intrinsic Value, Exercisable | $	27.3
Aggregate Intrinsic Value, Exercisable and expected to vest | $	30.5
Intrinsic value of options exercised | $	$ 2,200,000	$ 10,300,000