Postretirement Benefit Plans - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2020	Sep. 27, 2019	Oct. 02, 2020	Sep. 27, 2019
Pension
Net periodic benefit income
Service cost	$ 17	$ 21	$ 49	$ 39
Interest cost	68	76	205	180
Expected return on plan assets	(158)	(157)	(473)	(348)
Amortization of net actuarial loss (gain)	2	0	7	0
Amortization of prior service credit	(7)		(21)
Contractual termination benefits and effect of curtailments or settlements	0	5	1	6
Total net periodic benefit income	(78)	(55)	(232)	(123)
Other Benefits
Net periodic benefit income
Service cost	0	1	1	1
Interest cost	3	2	7	6
Expected return on plan assets	(5)	(5)	(15)	(13)
Amortization of net actuarial loss (gain)	(1)	(1)	(2)	(4)
Amortization of prior service credit	0		0
Contractual termination benefits and effect of curtailments or settlements	0	0	0	0
Total net periodic benefit income	$ (3)	$ (3)	$ (9)	$ (10)