Financial Instruments - Fair Value of Derivative Instruments (Details) - USD ($) $ in Millions		Mar. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Asset Derivatives		$ 570	$ 617
Liability Derivatives		499	630
Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Asset Derivatives		380	354
Liability Derivatives		338	383
Derivatives Designated as Hedging Instruments | Interest rate contracts
Derivatives, Fair Value [Line Items]
Asset Derivatives		30	17
Liability Derivatives		307	355
Derivatives Designated as Hedging Instruments | Net investment hedge derivative contracts
Derivatives, Fair Value [Line Items]
Asset Derivatives	[1]	350	337
Liability Derivatives	[1]	31	28
Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Asset Derivatives		190	263
Liability Derivatives		161	247
Derivatives Not Designated as Hedging Instruments | Currency exchange contracts
Derivatives, Fair Value [Line Items]
Asset Derivatives		69	72
Liability Derivatives		28	37
Derivatives Not Designated as Hedging Instruments | Commodity contracts
Derivatives, Fair Value [Line Items]
Asset Derivatives		121	191
Liability Derivatives		$ 133	$ 210

[1] Net investment hedge contracts consist of cross-currency interest rate swaps and forward contracts. We also designate some of our non-U.S. dollar denominated debt to hedge a portion of our net investments in our non-U.S. operations. This debt is not reflected in the table above, but is included in long-term debt discussed in Note 9, Debt and Borrowing Arrangements. Both net investment hedge derivative contracts and non-U.S. dollar denominated debt acting as net investment hedges are also disclosed in the Derivative Volume table and the Hedges of Net Investments in International Operations section appearing later in this footnote.