Revenue Recognition - Net Sales Disaggregated by Significant Products and Services (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 26, 2020	Jun. 27, 2020	Mar. 28, 2020	Dec. 28, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 29, 2018	Sep. 26, 2020	Sep. 28, 2019	Sep. 29, 2018
Disaggregation of Revenue [Line Items]
Net sales	$ 64,698	$ 59,685	$ 58,313	$ 91,819	$ 64,040	$ 53,809	$ 58,015	$ 84,310	$ 274,515	$ 260,174	$ 265,595
Revenue recognized that was included in deferred revenue at the beginning of the period									5,000	5,900	5,800
iPhone
Disaggregation of Revenue [Line Items]
Net sales									137,781	142,381	164,888
Mac
Disaggregation of Revenue [Line Items]
Net sales									28,622	25,740	25,198
iPad
Disaggregation of Revenue [Line Items]
Net sales									23,724	21,280	18,380
Wearables, Home and Accessories
Disaggregation of Revenue [Line Items]
Net sales									30,620	24,482	17,381
Services
Disaggregation of Revenue [Line Items]
Net sales									$ 53,768	$ 46,291	$ 39,748