Financial Instruments - Short-term Borrowings (Details) - USD ($) $ in Millions		Sep. 30, 2018	Dec. 31, 2017
Financial Instruments [Abstract]
Commercial paper		$ 2,600	$ 6,100
Current portion of long-term debt, principal amount		4,260	3,532
Other short-term borrowings, principal amount	[1]	537	320
Total short-term borrowings, principal amount		7,396	9,951
Net fair value adjustments related to hedging and purchase accounting		(5)	14
Net unamortized discounts, premiums and debt issuance costs		(7)	(12)
Total Short-term borrowings, including current portion of long-term debt, carried at historical proceeds, as adjusted	[2]	$ 7,385	$ 9,953

[1] Other short-term borrowings primarily include cash collateral. For additional information, see Note 7F.

[2] Amounts may not add due to rounding.