Income Taxes (Schedule of Net Deferred Tax Asset/Liability) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Employee benefits	$ 102	$ 111
Operating loss carryforwards	1,304	1,030
Capital loss carryforwards	2	3
Foreign tax credits	611	611
Other credit carryforwards	0	0
Investments in subsidiaries and affiliates	0	174
Other	5	69
Subtotal	2,024	1,998
Valuation allowance	(749)	(926)
Total deferred tax assets	1,275	1,072
Deferred tax liabilities:
Property, plant and equipment	1,018	1,332
Accrued revenue	60	81
Other	3	3
Total deferred tax liabilities	1,081	1,416
Net deferred tax liabilities		$ 344
Net deferred tax assets	$ 194