Reconciliation of the numerators and denominators (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Income Available to Ordinary Shareholders
Income from continuing operations	$ 1,513	$ 631	$ 1,100
Income from discontinued operations	124	0	4,574
Basic and diluted income available to shareholders	$ 1,637	$ 631	$ 5,674
Weighted Average Shares Outstanding
Basic weighted average shares outstanding	716.6	751.0	870.2
Stock options, unvested restricted stock and unvested performance share awards	4.5	2.6	4.1
Diluted weighted average shares outstanding	721.1	753.6	874.3
Antidilutive Securities
Options to purchase common shares	0.0	1.4	1.4

Antidilutive securities.

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