Quarterly Financial Data (Unaudited) Narrative (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loss Contingencies [Line Items]
Other Nonrecurring (Income) Expense	$ 1,600	$ 35	$ 108	$ 134	$ 245	$ 771	$ 347	$ 285			$ 11
Restructuring Charges									$ 183	$ 280	232
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount									0	137	265
Inventory Write-down									(540)	$ (269)	(244)
IRAQ
Loss Contingencies [Line Items]
Loss on Contracts									$ 0		$ 153