Balance sheet components - Accrued and other current liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Balance sheet components
Employee-related	$ 13,564	$ 18,654
Income and other taxes payable	1,304	3,956
Deferred revenue, current	1,065	956
Accrued warranty	582	678	$ 1,143	$ 1,175
Rusnano payment derivative	389	389
Asset sale related contingent liabilities (Note 5)	6,700
Transition service agreement related payables (Note 5)	7,742
Other accrued expenses	6,293	5,992
Accrued and other current liabilities	$ 37,639	$ 30,625