Income And Other Taxes (Deferred Income Taxes Assets And Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Income And Other Taxes [Abstract]
Property, plant and equipment	$ 35,745	$ 36,559
Other liabilities	6,516	5,625
Total deferred tax liabilities	42,261	42,184
Pension and other postretirement benefits	(4,115)	(4,338)
Asset retirement obligations	(4,118)	(4,237)
Tax loss carryforwards	(6,321)	(6,767)
Other assets	(5,498)	(5,832)
Total deferred tax assets	(20,052)	(21,174)
Asset valuation allowances	1,826	2,565
Net deferred tax liabilities	$ 24,035	$ 23,575