Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Libya statutory income tax rate		93.50%
Effective income tax rate excluding Libya		14.00%	5.00%
Change in valuation allowance	$ (28)	$ (177)	$ 446
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, Tax Settlement, Foreign, Amount	(126)
Operating loss carryforwards	1,685	1,304
Foreign tax credits	611	611
Deferred tax liability, property, plant and equipment	1,861	1,018
Income tax receivable, current	42
Interest and penalties recorded	6	2	$ 27
Interest and penalties accrued	3	$ 27
United States
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, subject to expiration	655
Operating loss carryforwards, not subject to expiration	829
State
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	181
Foreign
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 20