Other Non-current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Other Non-current Liabilities [Abstract]
Tax payable (note 8)	$ 25,958	$ 19,262
Finance lease obligation - non-current	7,875	3,284
Share unit liabilities	2,865	4,243
Other non-current liabilities	10,075	11,299
Other non-current liabilities, Total	$ 46,773	$ 38,088