Earnings Per Share (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Available to Ordinary Shareholders
Basic and diluted income available to shareholders	$ 118	$ 381
Weighted Average Shares Outstanding
Basic weighted average shares outstanding (in shares)	687.0	704.3
Effect of dilutive securities:
Stock options, unvested restricted stock and unvested performance share awards (in shares)	3.3	5.2
Diluted weighted average shares outstanding (in shares)	690.3	709.5
Antidilutive Securities
Stock options and unvested restricted stock (in shares)	0.3	0.0