Segment Information - Assets and Goodwill by Segment (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Assets, net of AHFS	$ 18,701	$ 18,419
Operating Segments | United States
Segment Reporting Information [Line Items]
Assets, net of AHFS	13,145	13,044
Operating Segments | Eastern Mediterranean
Segment Reporting Information [Line Items]
Assets, net of AHFS	2,728	2,630
Operating Segments | West Africa
Segment Reporting Information [Line Items]
Assets, net of AHFS	736	805
Operating Segments | Other Int'l
Segment Reporting Information [Line Items]
Assets, net of AHFS	119	37
Noble Midstream | United States
Segment Reporting Information [Line Items]
Assets, net of AHFS	1,801	1,742
Intersegment Eliminations
Segment Reporting Information [Line Items]
Assets, net of AHFS	(162)	(145)
Corporate
Segment Reporting Information [Line Items]
Assets, net of AHFS	$ 334	$ 306