Asset Impairments - Schedule of Non-Cash Asset Impairment Charges (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Asset Impairment Charges [Line Items]
Goodwill impairment charge	$ 1,547
Total	138,086	$ 19,359	$ 12,298
Proved Property [Member]
Asset Impairment Charges [Line Items]
Asset impairment charges	93,984	16,903	9,817
Unproved Property [Member]
Asset Impairment Charges [Line Items]
Asset impairment charges	$ 42,555	$ 2,456	$ 2,481