Balance sheet components (Details 8) - USD ($) $ in Thousands	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013
Accounts Payable And Accrued Liabilities Current [Abstract]
Employee-related	$ 13,519		$ 13,635
Accrued warranty	1,160	$ 1,254	1,751	$ 1,822	$ 1,811	$ 1,737
Penalty payment derivative	389		530
Deferred income tax liabilities	181		181
Other	6,157		6,631
Accrued and other current liabilities	$ 21,406		$ 22,728