Income Taxes - Valuation Allowance (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 27, 2019	Sep. 28, 2018
Valuation allowance
Valuation allowance	$ 4,970	$ 2,191
Increase in the valuation allowance for deferred tax assets	$ 2,891

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319

Name:	us-gaap_DeferredTaxAssetsValuationAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant