Consolidated Statements of Financial Position (Parenthetical) $ in Millions	Sep. 30, 2018 € / shares	Sep. 30, 2018 USD ($) $ / shares shares	Sep. 30, 2017 € / shares	Sep. 30, 2017 USD ($) $ / shares shares
Allowance for doubtful accounts \| $		$ 177		$ 182
Ordinary shares, par value \| $ / shares		$ 0.01		$ 0.01
Ordinary shares authorized		2,000,000,000		2,000,000,000
Ordinary shares issued		950,969,965		945,055,276
Preferred shares authorized		200,000,000		200,000,000
Preferred shares issued		0		0
Preferred shares, par or stated value per share \| $ / shares		$ 0.01		$ 0.01
Ordinary shares held in treasury, as cost		25,963,004		17,080,302
Common Class A [Member]
Ordinary shares, par value \| € / shares	€ 1.00		€ 1.00
Ordinary shares authorized		40,000		40,000
Ordinary shares issued		0		0

A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.4)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29,30)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 30
-Section 45
-Paragraph 1
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