Leases - Balance sheet and other information (Details) - USD ($) $ in Millions	Jun. 29, 2019	Dec. 29, 2018
Operating leases:
Other assets	$ 298
Other assets	us-gaap:OtherAssets
Other current liabilities	$ 53
Other current liabilities	us-gaap:OtherLiabilitiesCurrent
Other liabilities	$ 247
Other liabilities	us-gaap:OtherLiabilities
Finance leases:
Property, plant and equipment, less accumulated amortization of $51 million	$ 116
Property, plant and equipment, less accumulated amortization of $51 million	us-gaap:PropertyPlantAndEquipmentNet
Accumulated amortization	$ 4,317	$ 4,203
Short-term and current portion of long-term debt	$ 6
Short-term and current portion of long-term debt	us-gaap:DebtCurrent
Long-term debt	$ 77
Long-term debt	us-gaap:LongTermDebtAndCapitalLeaseObligations
Weighted-average remaining lease term (in years)
Finance leases	14 years 1 month 6 days
Operating leases	10 years 3 months 18 days
Weighted-average discount rate
Finance leases	2.73%
Operating leases	4.46%
Finance leased assets
Finance leases:
Accumulated amortization	$ 51