Stock-Based Compensation (Tables)

9 Months Ended

Sep. 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	(329,375)		19.74
Outstanding at September 30, 2019	1,330,088	$	36.04

Schedule of weighted average assumptions for employee grants

	Nine Months Ended
	September 30,
Valuation assumptions:	2019		2018
Expected volatility	69.30	%	58.40	%
Expected term (years)	6.03		6.08
Risk-free interest rate	2.48	%	2.41	%
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	689,875		55.05
Exercised	(231,790)		11.63
Forfeited	(107,350)		49.04
Outstanding at September 30, 2019	2,840,849	$	24.33	7.0	$	88,641
Options vested and expected to vest at September 30, 2019	2,840,849	$	24.33	7.0	$	88,641
Exercisable at September 30, 2019	1,585,816	$	11.64	5.7	$	68,877

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

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2019		2018		2019		2018
Cost of revenue - product	$	290	$	171	$	912	$	592
Cost of revenue - service		928		412		2,906		1,055
Research and development		2,053		912		6,141		1,431
Sales and marketing		1,132		401		3,224		1,172
General and administrative		2,822		1,100		7,800		2,871
Total stock-based compensation expense	$	7,225	$	2,996	$	20,983	$	7,121