Segment Information - Reportable Segments and Reconciliation to Consolidated Net Income (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
Segment Reporting Disclosure [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
Segment operating expenses																	88,810		73,707		60,417
Income from operations	591	[1]	(544)	[1]	(15)	[1]	146	[1]	510	[1]	(25)	[1]	79	[1]	181	[1]	178		745		676
Stock-based compensation																	(1,497)		(1,134)		(833)
Other operating income (expense), net																	(133)		(114)		(159)
Total non-operating income (expense)																	(289)		(239)		(132)
Provision for income taxes	205	[1]	(205)	[1]	94	[1]	73	[1]	179	[1]	(12)	[1]	13	[1]	(18)	[1]	(167)		(161)		(428)
Equity-method investment activity, net of tax																	37		(71)		(155)
Net income (loss)	214	[1]	(437)	[1]	(126)	[1]	108	[1]	239	[1]	(41)	[1]	(7)	[1]	82	[1]	(241)		274		(39)
Operating Segments
Segment Reporting Disclosure [Line Items]
Net sales																	88,988		74,452		61,093
Segment operating expenses																	87,180	[2]	72,459	[2]	59,425	[2]
Income from operations																			1,993		1,668
Operating Segments | North America
Segment Reporting Disclosure [Line Items]
Net sales																	55,469		44,517		34,813
Segment operating expenses																	53,364	[2]	42,631	[2]	33,221	[2]
Income from operations																	2,105		1,886		1,592
Operating Segments | International
Segment Reporting Disclosure [Line Items]
Net sales																	33,519		29,935		26,280
Segment operating expenses																	33,816	[2]	29,828	[2]	26,204	[2]
Income from operations																	$ (297)		$ 107		$ 76

[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] Represents operating expenses, excluding stock-based compensation and “Other operating expense (income), net,” which are not allocated to segments.