Income Tax (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Expense (Benefit)		$ 1,179	$ (1,470)	$ 693
Operating Expenses		13,714	$ 13,621	$ 13,749
Settlement with Taxing Authority
Tax Adjustments, Settlements, and Unusual Provisions	$ (349)
Income Tax Expense (Benefit)	(168)
Operating Expenses	229
Operating Expenses Net	$ 181
Certain State and Foreign Net Operating Loss Carryforwards
Valuation allowance, change during year		12
Foreign Currency Movement
Valuation allowance, change during year		$ (8)