Leases - Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 26, 2020	Dec. 31, 2019
Assets:
Operating lease assets	$ 472	$ 554
Finance lease assets	30	41
Total lease assets	$ 502	$ 595
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization	us-gaap:PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization
Current liabilities:
Operating lease liabilities	$ 123	$ 122
Finance lease liabilities	11	13
Total lease liabilities, current	$ 134	$ 135
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent	us-gaap:AccruedLiabilitiesCurrent
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:DebtCurrent	us-gaap:DebtCurrent
Non-current liabilities:
Operating lease liabilities	$ 401	$ 497
Finance lease liabilities	7	16
Total lease liabilities, non-current	$ 408	$ 513
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:LongTermDebtNoncurrent	us-gaap:LongTermDebtNoncurrent