Share-based Compensation (Tables)

6 Months Ended

Jun. 30, 2020

Share-based Compensation

Schedule of share-based compensation expense

	Three months ended June 30,				Six months ended June 30,
	2020		2019		2020		2019
	(in thousands)
Cost of sales	$	474	$	595	$	995	$	1,065
Research and development		613		982		1,486		1,775
Selling, general, and administrative		1,887		3,011		4,139		4,905
Total	$	2,974	$	4,588	$	6,620	$	7,745

Summary of stock option activity

		Weighted
	Number of	Average
	Shares	Exercise Price
	(in thousands)
Balance - December 31, 2019	1,119		34.88
Expired or forfeited	(324)		33.96
Balance - June 30, 2020	795		35.25

Summary of non-vested restricted and performance shares activity

		Weighted
		Average
	Number of	Grant Date
	Shares	Fair Value
	(in thousands)
Balance - December 31, 2019	2,257		16.20
Granted	983		9.32
Performance award adjustments	(45)		31.34
Vested	(572)		15.95
Forfeited	(348)		15.47
Balance - June 30, 2020	2,275		13.10