Income Taxes, Uncertain Tax Positions (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 28, 2019	Sep. 29, 2018
Gross Unrecognized Tax Benefits [Roll Forward]
Beginning unrecognized tax benefits	$ 74	$ 59
Gross increases - tax positions in prior periods	2	1
Gross increases - current period tax positions	6	19
Gross increases - from RPC acquisition	88	0
Settlements	(1)	0
Lapse of statue of limitations	(4)	(5)
Ending unrecognized tax benefits	165	$ 74
Unrecognized tax benefits that would affect effective tax rate if recognized	141
Interest and penalties accrued for uncertain tax positions	$ 36

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

Amount of unrecognized tax benefits.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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