Segment Information and Geographic Data - Summary Information by Reportable Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Apr. 01, 2017	Mar. 31, 2018	Apr. 01, 2017
Segment Reporting Information [Line Items]
Net sales	$ 61,137	$ 52,896	$ 149,430	$ 131,247
Operating income	15,894	14,097	42,168	37,456
Americas
Segment Reporting Information [Line Items]
Net sales	24,841	21,157	60,034	53,125
Operating income	7,768	6,668	19,084	17,162
Europe
Segment Reporting Information [Line Items]
Net sales	13,846	12,733	34,900	31,254
Operating income	4,259	3,851	11,152	9,587
Greater China
Segment Reporting Information [Line Items]
Net sales	13,024	10,726	30,980	26,959
Operating income	4,963	4,224	11,871	10,400
Japan
Segment Reporting Information [Line Items]
Net sales	5,468	4,485	12,705	10,251
Operating income	2,346	2,037	5,428	4,710
Rest of Asia Pacific
Segment Reporting Information [Line Items]
Net sales	3,958	3,795	10,811	9,658
Operating income	$ 1,278	$ 1,309	$ 3,853	$ 3,538