Goodwill and Other Intangible Assets - Changes in Carrying Value of Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2020	Sep. 30, 2019
Goodwill [Roll Forward]
Beginning balance	$ 6,705,507	$ 6,664,272
Goodwill recognized in connection with acquisitions		43,418
Foreign currency translation	1,212	(2,183)
Ending balance	6,706,719	6,705,507
Operating segments \| Pharmaceutical Distribution
Goodwill [Roll Forward]
Beginning balance	4,852,775	4,852,775
Goodwill recognized in connection with acquisitions		0
Foreign currency translation	0	0
Ending balance	4,852,775	4,852,775
Operating segments \| Other
Goodwill [Roll Forward]
Beginning balance	1,852,732	1,811,497
Goodwill recognized in connection with acquisitions		43,418
Foreign currency translation	1,212	(2,183)
Ending balance	$ 1,853,944	$ 1,852,732

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(10)(1))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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