Stockholders' Equity (Tables)
6 Months Ended
Mar. 31, 2015
Stockholders' Equity Note [Abstract]  
Schedule of Stock by Class
As-Converted Class A Common Stock. The number of shares of each class and the number of shares of class A common stock on an as-converted basis at March 31, 2015, are as follows:
(in millions, except conversion rates)
Shares Outstanding
 
Conversion Rate
Into Class A
Common Stock
 
As-converted Class A Common
Stock(1)
Class A common stock
1,964

 

 
1,964

Class B common stock
245

 
1.6483

(2) 
405

Class C common stock
20

 
4.0000

 
79

Total
 
 
 
 
2,448


(1) 
Figures in the table may not recalculate exactly due to rounding. As-converted class A common stock is calculated based on unrounded numbers.
(2) 
The class B to class A common stock conversion rate has been rounded for purposes of this disclosure. Conversion calculations for dividend payments are based on a conversion rate rounded to the tenth decimal.
Share Repurchase Program Disclosure
Reduction in as-converted class A common stock. The following table presents share repurchases in the open market.
(in millions, except per share data)
Three Months Ended
March 31, 2015
 
Six Months Ended
March 31, 2015
Shares repurchased in the open market (1)
16

 
29

Average repurchase price per share (2)
$
64.84

 
$
64.86

Total cost
$
1,052

 
$
1,855

(1)  
All shares repurchased in the open market have been retired and constitute authorized but unissued shares.
(2) 
Figures in the table may not recalculate exactly due to rounding. Average repurchase price per share is calculated based on unrounded numbers.