Property, Plant And Equipment (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 2,069	$ 1,910	$ 1,833
Interest capitalized	110	170	158
Rental expense for leased properties	283	287	267
Minimum rental payments under capital leases, total	147
Minimum rental payments under operating leases with initial or remaining terms of one year or more, total	1,355
Sublease payments under operating lease	13
Property, plant and equipment included in accounts payable	196	292
Property, Plant and Equipment [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 1,548	$ 1,418	$ 1,357