Segment Information - Net Sales of Similar Products and Services (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Revenue from External Customer [Line Items]
Net sales	$ 20,579		$ 17,092		$ 59,659		$ 48,865
Media
Revenue from External Customer [Line Items]
Net sales	5,244		5,033		15,555		14,488
Electronics and other general merchandise
Revenue from External Customer [Line Items]
Net sales	13,953		11,048		40,248		31,677
Other
Revenue from External Customer [Line Items]
Net sales	$ 1,382	[1]	$ 1,011	[1]	$ 3,856	[1]	$ 2,700	[1]

[1] Includes sales from non-retail activities, such as Amazon Web Services (“AWS”), advertising services, and our co-branded credit card agreements.