Share-based compensation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based compensation
Total	$ 3,783	$ 3,279	$ 11,528	$ 12,720
Cost of sales
Share-based compensation
Total	383	513	1,448	1,603
Research and development
Share-based compensation
Total	756	709	2,531	2,728
Selling, general and administrative
Share-based compensation
Total	$ 2,644	1,890	$ 7,549	7,393
Restructuring
Share-based compensation
Total		$ 167		$ 996
Restricted stock awards | Minimum
Share-based compensation
Expiration term			1 year
Restricted stock awards | Maximum
Share-based compensation
Expiration term			5 years
Stock options
Number of Shares
Outstanding at the beginning of the period (in shares)			1,222
Expired or forfeited (in shares)			(69)
Outstanding at the end of the period (in shares)	1,153		1,153
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)			$ 34.80
Expired or forfeited (in dollars per share)			33.62
Outstanding at the end of the period (in dollars per share)	$ 34.87		$ 34.87
Non-vested restricted shares and performance shares
Number of Shares
Outstanding at the beginning of the period (in shares)			2,218
Granted (in shares)			1,048
Performance award adjustments (in shares)			(25)
Vested (in shares)			(721)
Forfeited (in shares)			(176)
Outstanding at the end of the period (in shares)	2,344		2,344
Weighted Average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share)			$ 20.74
Granted (in dollars per share)			11.41
Performance award adjustments (in dollars per share)			28.91
Vested (in dollars per share)			22.29
Forfeited (in dollars per share)			19.41
Outstanding at the end of the period (in dollars per share)	$ 16.02		$ 16.02