Properties and Equipment, Net - Schedule of Aging of Capitalized Exploratory Costs (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Capitalized exploratory well costs that have been capitalized for a period of one year or less	$ 19,511	$ 0	$ 0
Capitalized exploratory well costs that have been capitalized for a period greater than one year	0	0	0
Capitalized exploratory well costs	$ 19,511	$ 0	$ 0	$ 10,557