Financial Instruments - Investments - Unrealized Gains and Losses Related to Equity Securities (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 28, 2020	Jun. 30, 2019	Jun. 28, 2020	Jun. 30, 2019
Financial Instruments [Abstract]
Net gains recognized during the period on investments in equity securities	[1],[2]	$ (732)	$ (36)	$ (478)	$ (147)
Less: Net (gains)/losses recognized during the period on equity securities sold during the period		1	(6)	(18)	(10)
Net unrealized gains during the reporting period on equity securities still held at the reporting date	[3]	$ (733)	$ (31)	$ (459)	$ (137)

[1] The gains in the second quarter of 2020 include, among other things, unrealized gains of $508 million related to our investment in Allogene and unrealized gains of $61 million related to our investment in BioNTech. The gains in the first six months of 2020 include, among other things, unrealized gains of $374 million related to our investment in Allogene and unrealized gains of $127 million related to our investment in BioNTech. The gains in the first six months of 2019 included, among other things, unrealized gains of $104 million related to our investment in Cortexyme, Inc. For additional information on investments, see Note 7B.

[2] The net gains on investments in equity securities are reported in Other (income)/deductions––net. For additional information, see Note 4.

[3]   Included in net unrealized gains are observable price changes on equity securities without readily determinable fair values. Since January 1, 2018, there were cumulative impairments and downward adjustments of $67 million and upward adjustments of $66 million. Impairments, downward and upward adjustments were not significant in the second quarter and the first six months of 2020 and 2019.