Stock-Based Compensation - Options Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Number of shares
Outstanding at beginning of period (in shares)	2,755,343
Granted (in shares)	5,000
Exercised (in shares)	(223,980)
Forfeited (in shares)	(37,700)
Outstanding at end of the period (in shares)	2,498,663
Options vested and expected to vest at end of the period (in shares)	2,498,663
Exercisable at end of period (in shares)	1,715,578
Weighted average exercise price
Outstanding at beginning of period (in dollars per share)	$ 25.10
Granted (in dollars per share)	68.10
Exercised (in dollars per share)	11.11
Forfeited (in dollars per share)	48.73
Outstanding at end of period (in dollars per share)	26.08
Options vested and expected to vest at end of period (in dollars per share)	26.08
Exercisable at end of period (in dollars per share)	$ 18.48
Weighted average remaining contractual term
Outstanding	6 years 7 months 6 days
Options vested and expected to vest at of the period	6 years 7 months 6 days
Exercisable	5 years 10 months 24 days
Aggregate intrinsic value
Outstanding (in dollars)	$ 73,296
Options vested and expected to vest at end of period (in dollars)	73,296
Exercisable (in dollars)	62,853
Additional disclosures
Intrinsic value of options exercised (in dollars)	9,656	$ 5,959
Proceeds from stock options exercised (in dollars)	2,312	$ 1,536
Stock options
Additional disclosures
Total unrecognized compensation cost (in dollars)	$ 19,044
Weighted average period expected to be recognized	2 years 3 months 18 days