Share-Based Payments (Tables)

6 Months Ended

Jun. 30, 2020

Share-based Payment Arrangement [Abstract]

Schedule of share-based compensation expense

Share-based compensation expense is as follows (dollars in thousands):

	Three Months ended June 30,				Six Months ended June 30,
	2020		2019		2020		2019
	(unaudited)				(unaudited)
Research and development	$	818	$	700	$	1,499	$	1,274
Selling, general and administrative	4,144		3,322		7,451		6,035
Total	$	4,962	$	4,022	$	8,950	$	7,309

Summary of stock options and SAR activities

The following table summarizes stock option and stock appreciation rights (SAR) activities:

	Number of Options	Weighted- Average Exercise Price (per share)		Weighted- Average Remaining Contractual Term (in years)
Outstanding, December 31, 2019	4,606,559	$	23.05	6.66
Granted	1,126,525	$	23.98
Exercised	(42,086)	$	11.58
Forfeited	(41,800)	$	26.66
Outstanding, June 30, 2020 (unaudited)	5,649,198	$	23.30	6.86
As of December 31, 2019:
Vested and expected to vest	4,606,559	$	23.05	6.66
Exercisable	2,598,112	$	15.68	5.48
As of June 30, 2020:
Vested and expected to vest	5,649,198	$	23.30	6.86
Exercisable	3,354,282	$	18.85	5.53