Segment Information - Reportable Segments and Reconciliation to Consolidated Net Income (Details) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) segment	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			3
Segment Reporting Disclosure [Line Items]
Net sales	$ 96,145	$ 69,981	$ 260,509	$ 193,086
Operating expenses	89,951	66,824	244,483	182,424
Operating income (loss)	6,194	3,157	16,026	10,662
Total non-operating income (expense)	615	(525)	387	(739)
Provision for income taxes	(569)	(494)	(2,298)	(1,588)
Equity-method investment activity, net of tax	91	(4)	(6)	(15)
Net income	6,331	2,134	14,109	8,320	$ 17,377	$ 11,347
North America
Segment Reporting Disclosure [Line Items]
Net sales	59,373	42,638	160,936	117,104
Operating expenses	57,121	41,356	155,232	111,971
Operating income (loss)	2,252	1,282	5,704	5,133
International
Segment Reporting Disclosure [Line Items]
Net sales	25,171	18,348	66,945	50,910
Operating expenses	24,764	18,734	66,590	51,986
Operating income (loss)	407	(386)	355	(1,076)
AWS
Segment Reporting Disclosure [Line Items]
Net sales	11,601	8,995	32,628	25,072
Operating expenses	8,066	6,734	22,661	18,467
Operating income (loss)	$ 3,535	$ 2,261	$ 9,967	$ 6,605