Stockholders' Equity - Schedule of Stock by Class (Details) shares in Millions	Mar. 31, 2026 shares	Sep. 30, 2025 shares
Schedule of Common Stock as Converted [Line Items]
Preferred stock, shares outstanding (in shares)	5	5
As-converted Class A Common Stock (in shares)	1,894	1,930
Series A preferred stock
Schedule of Common Stock as Converted [Line Items]
Preferred stock, shares outstanding (in shares)	0	0
Preferred stock, conversion rate into Class A Common Stock	100.0000	100.0000
As-converted Class A Common Stock (in shares)	7	8
Series B preferred stock
Schedule of Common Stock as Converted [Line Items]
Preferred stock, shares outstanding (in shares)	2	2
Preferred stock, conversion rate into Class A Common Stock	0.5960	0.6690
As-converted Class A Common Stock (in shares)	1	2
Series C preferred stock
Schedule of Common Stock as Converted [Line Items]
Preferred stock, shares outstanding (in shares)	3	3
Preferred stock, conversion rate into Class A Common Stock	0.7170	0.7640
As-converted Class A Common Stock (in shares)	2	2
Class A common stock
Schedule of Common Stock as Converted [Line Items]
Common stock, shares outstanding (in shares)	1,660	1,691
Common stock, conversion rate into Class A Common Stock	0	0
As-converted Class A Common Stock (in shares)	1,660	1,691
Class B-1 common stock
Schedule of Common Stock as Converted [Line Items]
Common stock, shares outstanding (in shares)	5	5
Common stock, conversion rate into Class A Common Stock	1.5475	1.5549
As-converted Class A Common Stock (in shares)	7	8
Class B-2 common stock
Schedule of Common Stock as Converted [Line Items]
Common stock, shares outstanding (in shares)	120	120
Common stock, conversion rate into Class A Common Stock	1.5075	1.5223
As-converted Class A Common Stock (in shares)	181	183
Class C common stock
Schedule of Common Stock as Converted [Line Items]
Common stock, shares outstanding (in shares)	9	9
Common stock, conversion rate into Class A Common Stock	4.0000	4.0000
As-converted Class A Common Stock (in shares)	36	36