Segment Information - Net Sales of Similar Products and Services (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Revenue from External Customer [Line Items]
Net sales	$ 29,328	[1]	$ 20,579	[1]	$ 19,340	[1]	$ 19,741	[1]	$ 25,587	[1]	$ 17,092	[1]	$ 15,704	[1]	$ 16,070	[1]	$ 88,988		$ 74,452		$ 61,093
Media
Revenue from External Customer [Line Items]
Net sales																	22,505		21,716		19,942
Electronics and other general merchandise
Revenue from External Customer [Line Items]
Net sales																	60,886		48,802		38,628
Other
Revenue from External Customer [Line Items]
Net sales																	$ 5,597	[2]	$ 3,934	[2]	$ 2,523	[2]

[1] The sum of quarterly amounts, including per share amounts, may not equal amounts reported for year-to-date periods. This is due to the effects of rounding and changes in the number of weighted-average shares outstanding for each period.

[2] Includes sales from non-retail activities, such as AWS, advertising services, and our co-branded credit card agreements.