Segment Information - Reportable Segments and Reconciliation to Consolidated Net Income (Details) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) segment	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			3
Segment Reporting Disclosure [Line Items]
Net sales	$ 43,744	$ 32,714	$ 117,413	$ 92,246
Operating expenses	43,397	32,139	115,434	89,315
Operating income (loss)	347	575	1,979	2,931
Total non-operating income (expense)	(31)	(84)	(44)	(205)
Provision for income taxes	(58)	(229)	(755)	(1,012)
Equity-method investment activity, net of tax	(2)	(10)	(4)	(92)
Net income	256	252	1,176	1,622	$ 1,926	$ 2,105
North America
Segment Reporting Disclosure [Line Items]
Net sales	25,446	18,874	68,808	53,544
Operating expenses	25,334	18,619	67,664	51,999
Operating income (loss)	112	255	1,144	1,545
International
Segment Reporting Disclosure [Line Items]
Net sales	13,714	10,609	36,259	30,019
Operating expenses	14,650	11,150	38,401	30,815
Operating income (loss)	(936)	(541)	(2,142)	(796)
AWS
Segment Reporting Disclosure [Line Items]
Net sales	4,584	3,231	12,346	8,683
Operating expenses	3,413	2,370	9,369	6,501
Operating income (loss)	$ 1,171	$ 861	$ 2,977	$ 2,182