Stock Plans and Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Assumptions Used in Determining Fair Value of Shares Issuable

The fair value of shares issuable under the ESPP is determined using the Black-Scholes option pricing model with the following weighted average assumptions: 

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Employee Stock Purchase Plan:
Expected term (in years) (1)		0.50		0.50		0.50		0.50
Expected volatility (2)	55% - 65%		45%		55% - 65%		45%
Risk-free interest rate (3)	0.12% - 0.29%		1.93% - 2.52%		0.12% - 0.29%		1.93% - 2.52%
Dividend rate (4)	0%		0%		0%		0%

⁽¹⁾ The expected term represents the contractual term of the ESPP;

⁽²⁾ The expected volatility of the Company’s common stock on the date of grant is based on the weighted average of the Company’s historical volatility as a public company, the implied volatility of publicly-traded options on the Company’s common stock and the volatilities of publicly traded peer companies that are reasonably comparable to the Company’s own operations;

⁽³⁾ The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant for zero coupon U.S. Treasury notes with maturities approximately equal to the expected term of the grant; and

⁽⁴⁾ The expected dividend yield is assumed to be zero as the Company has never paid dividends and has no current plans to pay any dividends on the Company’s common stock.

Schedule of Stock Option Activity

The following table summarizes the Company’s stock option activity:

	Stock options outstanding			Weighted average exercise price
Outstanding at December 31, 2019		723,383		$	26.56
Exercised		(275,309	)		24.57
Forfeited		(10,930	)		27.98
Outstanding at September 30, 2020		437,144			27.78

Schedule of Stock Options Outstanding, Vested and Expected to Vest and Exercisable

Stock options outstanding, vested and expected to vest and exercisable are as follows:

	As of September 30, 2020
	Number of shares		Remaining contractual life (years)		Weighted- average exercise price
Outstanding		437,144		6.81	$	27.78
Vested and expected to vest		430,921		6.81		27.71
Exercisable		155,028		6.07		21.06

Schedule of Vested and Nonvested Stock Option Activity

Vested and nonvested stock option activity was as follows:

	Vested				Nonvested
	Options outstanding		Weighted average exercise price		Options outstanding		Weighted average exercise price
Outstanding at September 30, 2020		155,028	$	21.06		282,116	$	31.47

Summary of RSU and PSU Activity

The following table summarizes the Company’s RSU and PSU activity:

	Number of Shares
Outstanding at December 31, 2019		1,314,791
Granted		494,266
Vested		(313,782	)
Forfeited		(19,101	)
Outstanding at September 30, 2020		1,476,174

Summary of Stock-Based Compensation Expense

The Company recorded the total stock-based compensation expense as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Cost of revenue	$	842	$	509	$	2,153	$	1,356
Sales and marketing		4,395		2,423		11,920		7,338
Research and development		2,571		1,732		6,743		5,560
General and administrative		5,543		3,637		14,123		9,840
Total	$	13,351	$	8,301	$	34,939	$	24,094