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Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended	12 Months Ended
	Dec. 29, 2017	Dec. 30, 2016	Sep. 28, 2018	Sep. 29, 2018
Income Tax Contingency [Line Items]
Federal statutory tax rate, percent	35.00%
Measurement period adjustments on effective tax rate	1 year
Provisional remeasurement income tax expense discrete benefit, deferred tax balances	$ (24)
Estimated valuation allowance	$ (53)
Effective income tax rate (percent)	93.90%	28.80%
Net discrete charge of tax cuts and jobs act	$ 29
Decrease in unrecognized tax benefits	$ 7
Scenario, Forecast
Income Tax Contingency [Line Items]
Federal statutory tax rate, percent			21.00%	24.60%

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Amount of decrease reasonably possible in the next twelve months for the unrecognized tax benefit.

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of income tax expense (benefit) from continuing operations attributable to an adjustment of a deferred tax liability or asset for enacted changes in tax laws or rates or a change in the tax status of the entity.

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