Condensed Consolidated Financial Statement Details - Property, Plant and Equipment, Net (Details) - USD ($) $ in Millions	Jun. 30, 2018	Sep. 30, 2017
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	$ 85,368	$ 75,076
Accumulated depreciation and amortization	(47,251)	(41,293)
Total property, plant and equipment, net	38,117	33,783
Land and buildings
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	15,409	13,587
Machinery, equipment and internal-use software
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	62,060	54,210
Leasehold improvements
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	$ 7,899	$ 7,279