Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2019

Stock-Based Compensation

Summary of restricted stock award activity

		Weighted
		average
	Number	grant-date
	of shares	fair value
Outstanding at December 31, 2018	1,070,061	$	20.61
Granted	589,402		54.93
Vested	(213,646)		22.02
Outstanding at June 30, 2019	1,445,817	$	34.40

Schedule of weighted average assumptions for employee grants

	Six Months Ended
	June 30,
Valuation assumptions:	2019		2018
Expected volatility	69.60	%	58.40	%
Expected term (years)	6.02		6.08
Risk-free interest rate	2.50	%	2.37	%
Dividend yield	—		—

Summary of stock option activity

				Weighted
		Weighted		average
		average		remaining	Aggregate
	Number	exercise		contractual	intrinsic
	of shares	price		term	value
Outstanding at December 31, 2018	2,490,114	$	15.70
Granted	669,250		54.90
Exercised	(134,715)		12.55
Forfeited	(76,370)		47.92
Outstanding at June 30, 2019	2,948,279	$	23.91	7.2	$	81,869
Options vested and expected to vest at June 30, 2019	2,948,279	$	23.91	7.2	$	81,869
Exercisable at June 30, 2019	1,540,073	$	10.43	5.8	$	60,826

Schedule of recorded stock-based compensation expense related to stock options

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2019		2018		2019		2018
Cost of revenue - product	$	313	$	171	$	622	$	421
Cost of revenue - service		994		373		1,978		643
Research and development		1,806		323		4,088		519
Sales and marketing		1,105		392		2,092		771
General and administrative		2,688		921		4,978		1,771
Total stock-based compensation expense	$	6,906	$	2,180	$	13,758	$	4,125