Fair Value (Liabilities Measured on Recurring Basis) (Parenthetical) (Details) - Redeemable Noncontrolling Interests - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Redemption of noncontrolling interests	$ 135	$ 0
Amounts reclassified into equity as a result of the expiration of a put arrangement	0	120
Current Liabilities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amount recorded in liabilities	$ 67	$ 0

The difference between the carrying amount of a financial instrument subject to a registration payment arrangement recorded as temporary equity prior to adoption of FSP EITF 00-19-2 and the carrying amount reclassified to permanent equity upon the adoption of FSP EITF 00-19-2. Recorded as a cumulative effect adjustment to the beginning balance of retained earnings. Does not apply to registration payment arrangements that are no longer outstanding upon adoption of FSP EITF 00-19-2.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 40
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=120519210&loc=d3e90193-114008

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section S99
-Paragraph 3A
-URI http://asc.fasb.org/extlink&oid=65877616&loc=SL6540498-122764

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Period Type:	duration