Exploratory Well Costs (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($)
CapitalizedExploratoryWellCostsAbstract [Line Items]
Balance at January 1	$ 17,253
Additions Pending the Determination of Proved Reserves	23,936
Reclassifications to Proved Properties	(26,499)
Costs Charged to Expense	(6,178)	[1]
Balance at September 30	$ 8,512

[1] Includes capitalized exploratory well costs charged to dry hole costs.