Retirement Plans - Amounts recognized in the balance sheets (Details) - USD ($) $ in Millions	Dec. 29, 2018	Dec. 30, 2017
Pension Benefits
Amounts recognized in our balance sheets
Non-current assets	$ 112	$ 106
Current liabilities	(27)	(27)
Non-current liabilities	(864)	(765)
Recognized in Accumulated other comprehensive loss, pre-tax:
Net loss (gain)	2,157	2,055
Prior service cost (credit)	69	64
Postretirement Benefits Other Than Pensions
Amounts recognized in our balance sheets
Current liabilities	(28)	(31)
Non-current liabilities	(222)	(258)
Recognized in Accumulated other comprehensive loss, pre-tax:
Net loss (gain)	(34)	(13)
Prior service cost (credit)	$ (27)	$ (33)

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Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

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Amount, before tax, of accumulated other comprehensive (income) loss for cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation of defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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Amount of asset, recognized in statement of financial position, for overfunded defined benefit pension and other postretirement plans.

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