Number of Shares of Class A Common Shares Outstanding on an As-Converted Basis (Detail) In Millions, unless otherwise specified	Jun. 30, 2014		Sep. 30, 2013
Schedule of Common Stock as Converted [Line Items]
As-converted Class A Common Stock	624	[1]
Class A common stock
Schedule of Common Stock as Converted [Line Items]
Shares Outstanding	496		508
Conversion Rate Into Class A Common Stock
As-converted Class A Common Stock	496	[1]
Class B common stock
Schedule of Common Stock as Converted [Line Items]
Shares Outstanding	245		245
Conversion Rate Into Class A Common Stock	0.4206
As-converted Class A Common Stock	103	[1]
Class C common stock
Schedule of Common Stock as Converted [Line Items]
Shares Outstanding	25		27
Conversion Rate Into Class A Common Stock	1.0000
As-converted Class A Common Stock	25	[1]

[1] Figures in the table may not recalculate exactly due to rounding. As-converted class A common stock is calculated based on whole numbers, not the rounded numbers presented.