Segment Information - Assets and Goodwill by Segment (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017	Apr. 24, 2017
Segment Reporting Information [Line Items]
Goodwill	$ 1,402	$ 1,310	$ 1,291
Assets, net of AHFS	22,448	21,476
Operating Segments | Eastern Mediter- ranean
Segment Reporting Information [Line Items]
Goodwill	0	0
Assets, net of AHFS	3,263	2,846
Operating Segments | West Africa
Segment Reporting Information [Line Items]
Goodwill	0	0
Assets, net of AHFS	1,306	1,308
Operating Segments | Other Int'l
Segment Reporting Information [Line Items]
Goodwill	0	0
Assets, net of AHFS	85	114
Operating Segments | United States
Segment Reporting Information [Line Items]
Goodwill	1,291	1,310
Assets, net of AHFS	15,622	15,767
Noble Midstream | United States
Segment Reporting Information [Line Items]
Goodwill	111	0
Assets, net of AHFS	2,141	1,357
Intersegment Eliminations
Segment Reporting Information [Line Items]
Goodwill	0	0
Assets, net of AHFS	(217)	(163)
Corporate
Segment Reporting Information [Line Items]
Goodwill	0	0
Assets, net of AHFS	$ 248	$ 247