Dispositions - United States E&P Segment (Details) - United States Exploration and Production [Member] - Gulf of Mexico Assets [Member] - Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] $ in Millions	3 Months Ended
	Sep. 30, 2018 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal of assets, net of cash transferred to the buyer	$ 16
Gain (loss) on disposal	$ 32