Revenue Recognition - Net Sales Disaggregated by Significant Products and Services (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 30, 2019	Mar. 31, 2018	Mar. 30, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Net sales	$ 58,015	$ 61,137	$ 142,325	$ 149,430
Revenue recognized that was included in deferred revenue at the beginning of the period	1,900	2,200	3,800	3,500
iPhone
Disaggregation of Revenue [Line Items]
Net sales	31,051	37,559	83,033	98,663
Mac
Disaggregation of Revenue [Line Items]
Net sales	5,513	5,776	12,929	12,600
iPad
Disaggregation of Revenue [Line Items]
Net sales	4,872	4,008	11,601	9,763
Wearables, Home and Accessories
Disaggregation of Revenue [Line Items]
Net sales	5,129	3,944	12,437	9,425
Services
Disaggregation of Revenue [Line Items]
Net sales	$ 11,450	$ 9,850	$ 22,325	$ 18,979