Divestitures (Details) $ in Millions	3 Months Ended
	Jun. 30, 2016 USD ($) a	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 31, 2015 USD ($)	Nov. 20, 2015 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of divestiture farmed out		35.00%	35.00%
Sales Proceeds		$ 238		$ 119
Alon A And Alon C [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity method investment, ownership percentage					47.00%
Total transaction value					$ 73
Cyprus Block 12 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total transaction value			$ 171
Proceeds received from farm-out agreement		131
Consideration subject to post-close adjustments		40
Certain US Crude Oil And Natural Gas Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales Proceeds		$ 20
Subsequent Event [Member] | Weld County, Colorado [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Purchase and sales agreement, area | a	33,100
Purchase and sales agreement, consideration	$ 505