Share-Based Payments (Tables)

9 Months Ended

Sep. 30, 2021

Share-based Payment Arrangement [Abstract]

Schedule of share-based compensation expense

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

	Three Months ended September 30,				Nine Months ended September 30,
	2021		2020		2021		2020
	(unaudited)				(unaudited)
Research and development	$	615	$	777	$	1,909	$	2,276
Selling, general and administrative	3,412		3,713		11,965		11,164
Total	$	4,027	$	4,490	$	13,874	$	13,440

Summary of stock options and SAR activities

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

	Number of Options	Weighted- Average Exercise Price (per share)		Weighted- Average Remaining Contractual Term (in years)
Outstanding, December 31, 2020	5,451,862	$	23.26	6.28
Granted	991,325	$	28.93
Exercised	(233,347)	$	18.82
Forfeited	(410,488)	$	27.43
Outstanding, September 30, 2021 (unaudited)	5,799,352	$	24.11	6.18
As of September 30, 2021:
Vested and expected to vest	5,799,352	$	24.11	6.18
Exercisable	3,679,177	$	21.23	4.80
As of December 31, 2020:
Vested and expected to vest	5,451,862	$	23.26	6.28
Exercisable	3,218,771	$	19.36	4.77

Summary of restricted stock units

The following table summarizes restricted stock unit (RSU) activities (unaudited):

	Number of RSUs	Weighted-Average Grant Date Fair Value per Share
Nonvested, December 31, 2020	26,055	$	23.99
Granted	21,110	$	29.61
Vested	(26,055)	$	23.99
Forfeited	—	$	—
Nonvested, September 30, 2021	21,110	$	29.61

Summary of performance stock unit

The following table summarizes performance share unit (PSU) activities (unaudited):

	Performance-Based Units			Market-Based Units			Total PSUs
	Number of PSUs	Weighted- Average Grant Date Fair Value per Share		Number of PSUs	Weighted- Average Grant Date Fair Value per Share		Number of PSUs	Weighted- Average Grant Date Fair Value per Share
Nonvested, December 31, 2020	—	$	—	15,625	$	23.41	15,625	$	23.41
Granted	95,000	29.74		20,000	28.63		115,000	$	29.55
Vested	(40,000)	29.61		—	—		(40,000)	$	29.61
Forfeited	(1,500)	30.45		—	—		(1,500)	$	30.45
Nonvested, September 30, 2021	53,500	$	29.82	35,625	$	26.34	89,125	$	28.43