Revenue Recognition - Net Sales Disaggregated by Significant Products and Services (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 26, 2020	Dec. 28, 2019
Disaggregation of Revenue [Line Items]
Net sales	$ 111,439	$ 91,819
Revenue recognized that was included in deferred revenue at the beginning of the period	2,500	1,900
iPhone
Disaggregation of Revenue [Line Items]
Net sales	65,597	55,957
Mac
Disaggregation of Revenue [Line Items]
Net sales	8,675	7,160
iPad
Disaggregation of Revenue [Line Items]
Net sales	8,435	5,977
Wearables, Home and Accessories
Disaggregation of Revenue [Line Items]
Net sales	12,971	10,010
Services
Disaggregation of Revenue [Line Items]
Net sales	$ 15,761	$ 12,715