Stock-Based Compensation - Restricted Stock Activity (Details) - Restricted stock units	6 Months Ended
	Jun. 30, 2019 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning unvested balance (shares) | shares	0
Granted (shares) | shares	173,733
Vested (shares) | shares	(1,106)
Canceled (shares) | shares	(30,410)
Ending unvested balance (shares) | shares	142,217
Beginning balance of options outstanding (in dollars per share) | $ / shares	$ 0.00
Granted (unaudited) (in dollars per share) | $ / shares	55.25
Vested (unaudited) (in dollars per share) | $ / shares	65.50
Canceled (unaudited) (in dollars per share) | $ / shares	42.72
Ending balance of options outstanding (in dollars per share) | $ / shares	$ 57.85