Share-based compensation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Share-based compensation
Total	$ 4,186	$ 4,388
Cost of sales
Share-based compensation
Total	657	546
Research and development
Share-based compensation
Total	429	1,099
Selling, general, and administrative
Share-based compensation
Total	$ 3,100	$ 2,743
Stock option Awards
Number of Shares
Outstanding at the beginning of the period (in shares)	1,576
Expired or forfeited (in shares)	(77)
Outstanding at the end of the period (in shares)	1,499
Weighted Average Exercise price
Outstanding at the beginning of the period (in dollars per share)	$ 35.18
Expired or forfeited (in dollars per share)	37.40
Outstanding at the end of the period (in dollars per share)	$ 35.06
Restricted Stock Awards | Minimum
Share-based compensation
Expiration term	1 year
Restricted Stock Awards | Maximum
Share-based compensation
Expiration term	5 years
Restricted shares and performance shares
Number of Shares
Outstanding at the beginning of the period (in shares)	1,949
Granted (in shares)	37
Released (in shares)	(53)
Forfeited (in shares)	(105)
Outstanding at the end of the period (in shares)	1,828
Weighted Average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share)	$ 23.85
Granted (in dollars per share)	26.80
Released (in dollars per share)	31.77
Forfeited (in dollars per share)	26.66
Outstanding at the end of the period (in dollars per share)	$ 23.88