Share-based compensation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Share-based compensation
Total	$ 3,157	$ 4,537
Cost of sales
Share-based compensation
Total	470	554
Research and development
Share-based compensation
Total	792	954
Selling, general and administrative
Share-based compensation
Total	$ 1,895	2,857
Restructuring
Share-based compensation
Total		$ 172
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)	(33)
Outstanding at the end of the period (in shares)	1,189
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 34.80
Expired or forfeited (in dollars per share)	33.82
Outstanding at the end of the period (in dollars per share)	$ 34.83
Non-vested restricted shares and performance shares
Number of Shares
Outstanding at the beginning of the period (in shares)	2,218
Granted (in shares)	974
Performance award adjustments (in shares)	(9)
Vested (in shares)	(156)
Forfeited (in shares)	(89)
Outstanding at the end of the period (in shares)	2,938
Weighted Average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share)	$ 20.74
Granted (in dollars per share)	11.32
Performance award adjustments (in dollars per share)	32.67
Vested (in dollars per share)	21.71
Forfeited (in dollars per share)	21.84
Outstanding at the end of the period (in dollars per share)	$ 17.50