Long-Lived Asset Impairments Narrative (Details) - USD ($) $ in Millions	1 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 13, 2019	Dec. 31, 2020	Dec. 31, 2018
Impaired Long-Lived Assets Held and Used [Line Items]
Long-lived Asset Impairments	$ 0	$ 20	$ 814	$ 151
Impairment of Long-Lived Assets to be Disposed of			571
Impairment of Intangible Assets (Excluding Goodwill)			155
Operating Lease, Right-of-Use Asset, Impairment Charge			88
Long-lived Asset Impairments	$ 0	20	814	151
Western Hemisphere [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Long-lived Asset Impairments			415
Impairment of Long-Lived Assets to be Disposed of			316
Impairment of Intangible Assets (Excluding Goodwill)			43
Operating Lease, Right-of-Use Asset, Impairment Charge			56
Long-lived Asset Impairments		13		46
Eastern Hemisphere [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Long-lived Asset Impairments			399
Impairment of Long-Lived Assets to be Disposed of			255
Impairment of Intangible Assets (Excluding Goodwill)			112
Operating Lease, Right-of-Use Asset, Impairment Charge			$ 32
Long-lived Asset Impairments		$ 7		$ 105