Leases (Details) - USD ($) $ in Millions		3 Months Ended		12 Months Ended
		Mar. 23, 2019		Dec. 29, 2018	Dec. 30, 2017
Leases [Abstract]
lessee, operating lease, amortization amount included in operating lease cost		$ 74
Lessee, Operating Lease, Term of Contract-Low End		1 year
Lessee, Operating Lease, Term of Contract-High End		20 years
Lessee, Operating Lease, Option to Extend		P5Y
Operating Lease, Weighted Average Remaining Lease Term		6 years
Operating Lease, Right-of-Use Asset		$ 1,416
Operating Lease, Payments		96
Operating Lease, Expense	[1]	85
Operating Leases, Rent Expense				$ 771	$ 742
Operating Leases, Future Minimum Payments Due, Next Twelve Months		343	[2]	459
Operating Leases, Future Minimum Payments, Due in Two Years		394		406
Operating Leases, Future Minimum Payments, Due in Three Years		288		294
Operating Leases, Future Minimum Payments, Due in Four Years		207		210
Operating Leases, Future Minimum Payments, Due in Five Years		126		161
Operating Leases, Future Minimum Payments, Due Thereafter		304		310
Operating Leases, Future Minimum Payments Due		1,662		$ 1,840
Variable Lease, Cost	[3]	19
Short-term Lease, Cost	[4]	84
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability		59
Operating Lease, Liability, Current		380
Operating Lease, Liability, Noncurrent		$ 1,069
Operating Lease, Weighted Average Discount Rate, Percent		4.00%
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		$ (213)
Operating Lease, Liability		$ 1,449
Lessee, Operating Sublease, Option to Terminate		P1Y

[1] Includes right-of-use asset amortization of $74 million

[2] Excluding the 12 weeks ended March 23, 2019.

[3] Primarily related to adjustments for inflation, common area maintenance and property tax.

[4] Not recorded on our balance sheet.