Stock-based awards (Tables)

3 Months Ended

Mar. 31, 2020

Stock-based awards

Schedule of assumptions used to determine grant-date fair value of stock options granted

	Three Months Ended
	March 31,
	2020			2019
Expected term (in years)		6.0		6.0
Volatility		80.60	%	67.44	%
Risk-free interest rate		1.63	%	2.57	%
Dividend yield		0	%	0	%

Summary of stock option activity

		Weighted-		Weighted-
		Average		Average	Aggregate
		Exercise		remaining	Intrinsic
	Number	Price per		contractual	Value
	of Options	Share		term (years)	(000's)
Balance outstanding, December 31, 2019	3,096,555	$	7.89	9.19	$	44,323
Options granted	103,500		20.08
Options exercised	(103,385)		1.09
Options cancelled	(1,220)		0.62
Balance outstanding, March 31, 2020	3,095,450	$	8.53	8.98	$	39,285
Exercisable, March 31, 2020	264,176	$	7.76	8.83	$	3,550
Vested and expected to vest, March 31, 2020	3,095,450	$	8.53	8.98	$	39,285