Other current assets - Schedule of Other Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Derivative instruments	$ 7,363	$ 3,324
Advances to suppliers	2,516	1,091
Receivables from statutory authorities	13,927	11,870
Others	1,735	4,883
Other current assets	$ 25,541	$ 21,168