Share-Based Payments

6 Months Ended

Jun. 30, 2020

Share-based Payment Arrangement [Abstract]

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

Stock Option and Stock Appreciation Rights

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

Restricted Stock Units

During the six months ended June 30, 2020, the Company granted 26,055 RSUs with a weighted average grant date fair value per share of $23.99, which generally vest one year from the date of grant.

Performance Stock Units

Performance-Based Awards

During the six months ended June 30, 2020, the Company granted 31,250 performance-based awards, with a weighted average grant date fair value per share of $21.35, which require certain performance targets to be achieved in order for these awards to vest. Vesting is subject to continued service requirements through the date that the achievement of the performance target is certified.

Market-Based Awards

During the six months ended June 30, 2020, the Company granted 15,625 market-based awards, with a weighted average grant date fair value per share of $23.41, which are subject to market-based performance targets in order for these awards to vest.