CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares shares in Millions	Sep. 30, 2019	Sep. 30, 2018
Series A convertible participating preferred stock
Preferred stock, shares issued (in shares)	0	0
Series B convertible participating preferred stock
Preferred stock, shares issued (in shares)	2	2
Preferred stock, shares outstanding (in shares)	2	2
Series C convertible participating preferred stock
Preferred stock, shares issued (in shares)	3	3
Preferred stock, shares outstanding (in shares)	3	3
Class A common stock
Common stock, par value (USD per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	2,001,622	2,001,622
Common stock, shares, issued (in shares)	1,718	1,768
Common stock, shares, outstanding (in shares)	1,718	1,768
Class B common stock
Common stock, par value (USD per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	622	622
Common stock, shares, issued (in shares)	245	245
Common stock, shares, outstanding (in shares)	245	245
Class C common stock
Common stock, par value (USD per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	1,097	1,097
Common stock, shares, issued (in shares)	11	12
Common stock, shares, outstanding (in shares)	11	12
Preferred Stock
Preferred stock, par value (USD per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	25	25
Preferred stock, shares issued (in shares)	5	5
Preferred stock, shares outstanding (in shares)	5	5