Pension, Retiree Medical and Savings Plans (Estimated Future Benefit Payments) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 20, 2021	Dec. 25, 2021	Dec. 26, 2020	Dec. 28, 2019	Dec. 29, 2018
Member-Plan A [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions/funding			$ 325	$ 400	$ 1,400
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions/funding			387	550
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Discretionary			339	417	1,417
Non-discretionary			168	255	198
2020			925
2021			1,080
2022			915
2023			960
2024			990
2025-29			5,270
Employer contributions/funding			507	672	1,615
Retiree Medical Plan
Defined Benefit Plan Disclosure [Line Items]
Discretionary			0	0	37
Non-discretionary			55	44	56
2020			95
2021			95
2022			90
2023			85
2024			80
2025-29			370
Employer contributions/funding			55	$ 44	$ 93
Years 2025 Through 2029
Defined Benefit Plan Disclosure [Line Items]
Subsidies expected to be received under the 2003 Medicare Act			4
Maximum | Years 2020 Through 2024
Defined Benefit Plan Disclosure [Line Items]
Subsidies expected to be received under the 2003 Medicare Act			$ 1
Forecast [Member] | Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Non-discretionary	$ 160
Forecast [Member] | Retiree Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Non-discretionary	$ 50
Forecast [Member] | Domestic - Plan A [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions/funding		$ 200
Forecast [Member] | Defined benefit plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions/funding		500
Forecast [Member] | Domestic plan -Plan H [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions/funding		$ 300