Segment Information and Geographic Data - Summary Information by Reportable Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 30, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net sales	$ 88,293	$ 78,351
Operating income	26,274	23,359
Americas
Segment Reporting Information [Line Items]
Net sales	35,193	31,968
Operating income	11,316	10,494
Europe
Segment Reporting Information [Line Items]
Net sales	21,054	18,521
Operating income	6,893	5,736
Greater China
Segment Reporting Information [Line Items]
Net sales	17,956	16,233
Operating income	6,908	6,176
Japan
Segment Reporting Information [Line Items]
Net sales	7,237	5,766
Operating income	3,082	2,673
Rest of Asia Pacific
Segment Reporting Information [Line Items]
Net sales	6,853	5,863
Operating income	$ 2,575	$ 2,229