CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2013	Sep. 30, 2012
Preferred Stock
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	25	25
Preferred stock, shares issued	0	0
Class A common stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	2,001,622	2,001,622
Common stock, shares issued	519	535
Common stock, shares outstanding	519	535
Class B common stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	622	622
Common stock, shares issued	245	245
Common stock, shares outstanding	245	245
Class C common stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	1,097	1,097
Common stock, shares issued	29	31
Common stock, shares outstanding	29	31