Stock Based Compensation (Tables)

3 Months Ended

Mar. 31, 2020

Equity [Abstract]

Summary of Stock Option Activity

A summary of the stock option activity under the Company’s plans for the three months ended March 31, 2020 is as follows:

	Number of Shares	Weighted Average Exercise Price
Options outstanding at December 31, 2019	5,318,759	$	9.97
Options granted	571,316	$	28.36
Less:
Options exercised	504,127	$	7.58
Options canceled or expired	51,210	$	14.61
Options outstanding at March 31, 2020	5,334,738	$	12.14
Exercisable at March 31, 2020	2,535,621	$	8.35

Summary of Fair Value of Each Stock Option Award Granted

The fair value of each stock option award granted during the three months ended March 31, 2020 was estimated as of the grant date using a trinomial lattice model with the following weighted average assumptions:

	Three Months Ended March 31, 2020
Expected term (in years)	4.0 - 5.5
Risk-free interest rate (%)	0.9%
Expected volatility (%)	39.9% - 44.5%
Dividend yield (%)	—
Weighted average fair value/share at grant date	$8.90

Summary of Restricted Stock Activity

A summary of the restricted stock activity under the Company’s plans for the three months ended March 31, 2020 is as follows:

	Number of Restricted Shares	Weighted Average Grant Date Fair Value
Nonvested at December 31, 2019	335,298	$	15.75
Granted	88,736	$	28.36
Vested	(37,674)	$	19.29
Forfeited	(4,585)	$	19.66
Nonvested at March 31, 2020	381,775	$	18.29