v2.4.0.8
Number of Shares of Class A Common Shares Outstanding on an As-Converted Basis (Detail)
In Millions, unless otherwise specified
Dec. 31, 2013
Sep. 30, 2013
Schedule of Common Stock as Converted [Line Items]    
As-converted Class A Common Stock 634 [1]  
Class A common stock
    
Schedule of Common Stock as Converted [Line Items]    
Shares Outstanding 505 508
Conversion Rate Into Class A Common Stock     
As-converted Class A Common Stock 505 [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 26 27
Conversion Rate Into Class A Common Stock 1.0000  
As-converted Class A Common Stock 26 [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.