Share-Based Payments (Tables)

6 Months Ended

Jun. 30, 2019

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of share-based compensation expense

Share-based compensation expense is as follows, in thousands of dollars:

	Three Months ended June 30,				Six Months ended June 30,
	2019		2018		2019		2018
	(unaudited)				(unaudited)
Research and development	$	700	$	534	$	1,274	$	952
Selling, general and administrative	3,322		2,534		6,035		4,751
Total	$	4,022	$	3,068	$	7,309	$	5,703

Summary of stock options and SAR activities

The following table summarizes stock options and SAR activities:

	Number of Options		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)
Outstanding, December 31, 2018	3,916,963		$	19.98	7.10
Granted (unaudited)	840,435		$	36.76
Exercised (unaudited)	(83,503	)	$	12.53
Forfeited (unaudited)	(28,024	)	$	36.13
Outstanding, June 30, 2019 (unaudited)	4,645,871		$	23.05	7.15
As of December 31, 2018:
Vested and expected to vest	3,916,963		$	19.98	7.10
Exercisable	1,889,947		$	12.47	5.96
As of June 30, 2019:
Vested and expected to vest (unaudited)	4,645,871		$	23.05	7.15
Exercisable (unaudited)	2,593,729		$	15.48	5.98