Income Taxes (Schedule of Net Deferred Tax Asset/Liability) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Employee benefits	$ 90	$ 75
Operating loss carryforwards	1,685	1,304
Capital loss carryforwards	1	2
Foreign tax credits	611	611
Other	27	4
Subtotal	2,414	1,996
Valuation allowance	(699)	(721)
Total deferred tax assets	1,715	1,275
Deferred tax liabilities:
Property, plant and equipment	1,861	1,018
Accrued revenue	40	60
Other	0	3
Total deferred tax liabilities	1,901	1,081
Net deferred tax liabilities	186	0
Net deferred tax assets	$ 0	$ 194