Shareholders' Equity - Changes in AOCI (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2019	Jul. 01, 2018
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance		$ (3,778)	$ (2,820)
Cumulative effect adjustments	[1]		(638)
Other comprehensive income, pretax		346	(73)
Provision for income tax, net		(44)	(27)
Other comprehensive loss, net of tax		302	(100)
Ending Balance		(3,476)	(3,558)
Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance		(71)	(94)
Cumulative effect adjustments	[1]		(4)
Other comprehensive income, pretax		68	(21)
Provision for income tax, net		(16)	7
Other comprehensive loss, net of tax		52	(14)
Ending Balance		(19)	(112)
Unrealized Gains on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance		0	19
Cumulative effect adjustments	[1]		(19)
Other comprehensive income, pretax		0	0
Provision for income tax, net		0	0
Other comprehensive loss, net of tax		0	0
Ending Balance		0	0
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance		102	402
Cumulative effect adjustments	[1]		0
Other comprehensive income, pretax		156	(215)
Provision for income tax, net		0	0
Other comprehensive loss, net of tax		156	(215)
Ending Balance		258	187
Changes in Retirement Plans’ Funded Status
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance		(3,809)	(3,147)
Cumulative effect adjustments	[1]		(615)
Other comprehensive income, pretax		122	163
Provision for income tax, net		(28)	(34)
Other comprehensive loss, net of tax		94	129
Ending Balance		$ (3,715)	$ (3,633)

[1] Reflects the cumulative effects of ASU 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, and ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income, which we adopted on January 1, 2018.