Basis of Presentation and Significant Accounting Policies - Impact of Adoption of Accounting Standards Related to Classification of Certain Transactions in the Statement of Cash Flows (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2018	Oct. 01, 2017
Operating Activities
Other adjustments, net	[1]	$ (1,169)	$ (604)
Other changes in assets and liabilities, net of acquisitions and divestitures	[1]	(2,441)	(3,616)
Investing Activities
Proceeds from redemptions/sales of short-term investments	[1]	12,752	5,778
Proceeds from redemptions/sales of long-term investments	[1]	2,174	2,403
Financing Activities
Principal payments on short-term borrowings	[1]	(4,239)	(7,659)
Net proceeds from short-term borrowings with original maturities of three months or less	[1]	(973)	566
Net increase in cash and cash equivalents and restricted cash and cash equivalents	[1]	2,227	193
Cash and cash equivalents and restricted cash and cash equivalents, beginning	[1]	1,431	2,666
Cash and cash equivalents and restricted cash and cash equivalents, end	[1]	3,658	2,858
As Previously Reported [Member]
Operating Activities
Other adjustments, net			(561)
Other changes in assets and liabilities, net of acquisitions and divestitures			(3,644)
Investing Activities
Proceeds from redemptions/sales of short-term investments			5,783
Proceeds from redemptions/sales of long-term investments			2,417
Financing Activities
Principal payments on short-term borrowings			(7,691)
Net proceeds from short-term borrowings with original maturities of three months or less			555
Net increase in cash and cash equivalents and restricted cash and cash equivalents			184
Cash and cash equivalents and restricted cash and cash equivalents, beginning			2,595
Cash and cash equivalents and restricted cash and cash equivalents, end			2,779
Cash Flow Classification [Member] | Effect of Change Higher/(Lower) [Member]
Operating Activities
Other adjustments, net			(43)
Financing Activities
Principal payments on short-term borrowings			33
Net proceeds from short-term borrowings with original maturities of three months or less			10
Restricted Cash [Member]
Financing Activities
Net increase in cash and cash equivalents and restricted cash and cash equivalents		$ 10
Restricted Cash [Member] | Effect of Change Higher/(Lower) [Member]
Operating Activities
Other changes in assets and liabilities, net of acquisitions and divestitures			28
Investing Activities
Proceeds from redemptions/sales of short-term investments			(5)
Proceeds from redemptions/sales of long-term investments			(14)
Financing Activities
Net increase in cash and cash equivalents and restricted cash and cash equivalents			9
Cash and cash equivalents and restricted cash and cash equivalents, beginning			70
Cash and cash equivalents and restricted cash and cash equivalents, end			$ 79

[1] Amounts may not add due to rounding.