Earnings per Share (EPS) and Common Stock - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2025	Mar. 31, 2024	Oct. 01, 2024	Sep. 30, 2024
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Anti-dilutive shares	300,000	100,000	200,000	100,000
Common stock, shares authorized	500,000,000		500,000,000			500,000,000
Stock repurchased during period (in shares)	500,000	0	800,000	0
Stock repurchased during period, value	$ 75		$ 150
Maximum [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Common stock, shares authorized	500,000,000		500,000,000
Stock authorized to repurchase					$ 2,000