Segment Information - Reportable Segments and Reconciliation to Consolidated Net Income (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended				12 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014	Sep. 30, 2013
Segment Reporting Disclosure [Line Items]
Net sales	$ 20,579		$ 17,092		$ 59,659		$ 48,865
Segment operating expenses	21,123		17,117		60,071		48,630
Income (loss) from operations	(544)		(25)		(412)		235
Stock-based compensation	(377)		(281)		(1,089)		(808)		(1,414)	(1,043)
Other operating income (expense), net	(31)		(11)		(94)		(74)
Total non-operating income (expense)	(90)		(18)		(128)		(181)
Benefit (provision) for income taxes	205		12		38		18
Equity-method investment activity, net of tax	(8)		(10)		47		(38)
Net income (loss)	(437)		(41)		(455)		34		(216)	132
Operating Segments
Segment Reporting Disclosure [Line Items]
Net sales	20,579		17,092		59,659		48,865
Segment operating expenses	20,715	[1]	16,825	[1]	58,888	[1]	47,748	[1]
Income (loss) from operations	(136)		267		771		1,117
Operating Segments | North America
Segment Reporting Disclosure [Line Items]
Net sales	12,867		10,301		36,722		29,186
Segment operating expenses	12,779	[1]	10,006	[1]	35,634	[1]	28,024	[1]
Income (loss) from operations	88		295		1,088		1,162
Operating Segments | International
Segment Reporting Disclosure [Line Items]
Net sales	7,712		6,791		22,937		19,679
Segment operating expenses	7,936	[1]	6,819	[1]	23,254	[1]	19,724	[1]
Income (loss) from operations	$ (224)		$ (28)		$ (317)		$ (45)

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