Share-based compensation (Tables)

6 Months Ended

Jun. 30, 2018

Share-based compensation

Schedule of share-based compensation expense

	Three months ended June 30,				Six months ended June 30,
	2018		2017		2018		2017
	(in thousands)
Cost of sales	$	536	$	500	$	1,090	$	1,157
Research and development	1,065		708		2,019		1,137
Selling, general, and administrative	2,646		3,368		5,503		6,468
Restructuring	657		841		829		841
Acquisition costs	—		4,203		—		4,203
Total	$	4,904	$	9,620	$	9,441	$	13,806

Summary of stock option activity

	Number of		Weighted Average
	Shares		Exercise Price
	(in thousands)
Balance - December 31, 2017	1,394		$	34.97
Expired or forfeited	(118	)	37.42
Balance - June 30, 2018	1,276		$	34.75

Summary of restricted and performance shares activity

			Weighted Average
	Number of		Grant Date
	Shares		Fair Value
	(in thousands)
Balance - December 31, 2017	1,880		$	25.41
Granted	824		19.39
Performance award adjustments	(5	)	32.67
Vested	(468	)	26.19
Forfeited	(109	)	26.06
Balance - June 30, 2018	2,122		$	22.85