CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares shares in Millions	Sep. 30, 2020	Sep. 30, 2019
Preferred Stock
Preferred stock, par value (in dollars 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
Series A convertible participating preferred stock
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (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 (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	2,001,622	2,001,622
Common stock, shares, issued (in shares)	1,683	1,718
Common stock, shares, outstanding (in shares)	1,683	1,718
Class B common stock
Common stock, par value (in dollars 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 (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	1,097	1,097
Common stock, shares, issued (in shares)	11	11
Common stock, shares, outstanding (in shares)	11	11