Share-based compensation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-based compensation
Total	$ 4,537	$ 4,186
Cost of sales
Share-based compensation
Total	554	657
Research and development
Share-based compensation
Total	954	429
Selling, general, and administrative
Share-based compensation
Total	2,857	$ 3,100
Restructuring
Share-based compensation
Total	$ 172
Restricted share awards | Minimum
Share-based compensation
Expiration term	1 year
Restricted share awards | Maximum
Share-based compensation
Expiration term	5 years
Stock options
Number of Shares
Outstanding at the beginning of the period (in shares)	1,394
Expired or forfeited (in shares)	(53)
Outstanding at the end of the period (in shares)	1,341
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 34.97
Expired or forfeited (in dollars per share)	35.45
Outstanding at the end of the period (in dollars per share)	$ 34.95
Non-vested restricted shares and performance shares
Number of Shares
Outstanding at the beginning of the period (in shares)	1,880
Granted (in shares)	759
Performance award adjustments (in shares)	(5)
Vested (in shares)	(44)
Forfeited (in shares)	(55)
Outstanding at the end of the period (in shares)	2,535
Weighted Average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share)	$ 25.41
Granted (in dollars per share)	19.69
Performance award adjustments (in dollars per share)	32.67
Vested (in dollars per share)	28.46
Forfeited (in dollars per share)	25.87
Outstanding at the end of the period (in dollars per share)	$ 23.62