Financial Instruments - Long-Term Debt (Details) - USD ($) $ in Millions		Apr. 01, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Net fair value adjustments related to hedging and purchase accounting		$ 10	$ 14
Net unamortized discounts, premiums and debt issuance costs		(8)	(12)
Total long-term debt, carried at historical proceeds, as adjusted	[1]	31,831	33,538
Current portion of long-term debt, carried at historical proceeds	[1]	4,763	3,546
Unsecured Debt [Member]
Debt Instrument [Line Items]
Total long-term debt, principal amount		31,484	32,783
Net fair value adjustments related to hedging and purchase accounting		461	872
Net unamortized discounts, premiums and debt issuance costs		(122)	(125)
Other long-term debt		8	8
Total long-term debt, carried at historical proceeds, as adjusted		31,831	33,538
Current portion of long-term debt, carried at historical proceeds		$ 4,763	$ 3,546

[1] Amounts may not add due to rounding.