Equity and Noncontrolling Interests - Redeemable Noncontrolling Interest (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Stockholders' equity attributable to noncontrolling interest	$ 325
Net income	30	$ 24	$ 25
Dividends	(61)	(56)	(58)
Stockholders' equity attributable to noncontrolling interest	341	325
Redeemable Noncontrolling Interest
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Stockholders' equity attributable to noncontrolling interest	47	28	34
Foreign currency translation adjustments	3	1	0
Dividends	(29)	(7)	(31)
Change in noncontrolling interest share	0	1	0
Stockholders' equity attributable to noncontrolling interest	$ 51	$ 47	$ 28

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which is directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent (that is, noncontrolling interest, previously referred to as minority interest).

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-Section S99
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Decrease in noncontrolling interest balance from payment of dividends or other distributions by the non-wholly owned subsidiary or partially owned entity, included in the consolidation of the parent entity, to the noncontrolling interest holders.

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Amount of Net Income (Loss) attributable to redeemable noncontrolling interest.

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Adjustments to temporary equity resulting from foreign currency translation adjustments.

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