Reconciliation of the numerators and denominators (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Income Available to Ordinary Shareholders
Income from continuing operations	$ 1,654	$ 732	$ 814
Income (loss) from discontinued operations	(43)	(1,600)	749
Basic and diluted income (loss) available to shareholders	$ 1,611	$ (868)	$ 1,563
Weighted Average Shares Outstanding
Basic weighted average shares outstanding	935.3	667.4	655.2
Stock options, unvested restricted stock and unvested performance share awards	9.3	5.2	6.3
Diluted weighted average shares outstanding	944.6	672.6	661.5
Antidilutive Securities
Options to purchase common shares	0.2	0.0	0.4