Segment Information - Narrative (Details)	12 Months Ended
Sep. 30, 2023 segment customer	Sep. 30, 2022 customer	Sep. 30, 2021 customer
Segment Reporting Information [Line Items]
Number of fundamental operations	2
Number of reportable segments	2
Recorded Music And Music Publishing Segments \| Sales Revenue, Net \| Credit Concentration Risk
Segment Reporting Information [Line Items]
Number of customers \| customer	3	3	3
Recorded Music And Music Publishing Segments \| Sales Revenue, Net \| Credit Concentration Risk \| Spotify
Segment Reporting Information [Line Items]
Customer concentration percentage (as a percent)	18.00%	17.00%	18.00%
Recorded Music And Music Publishing Segments \| Sales Revenue, Net \| Credit Concentration Risk \| YouTube
Segment Reporting Information [Line Items]
Customer concentration percentage (as a percent)	12.00%	12.00%	11.00%
Recorded Music And Music Publishing Segments \| Sales Revenue, Net \| Credit Concentration Risk \| Apple
Segment Reporting Information [Line Items]
Customer concentration percentage (as a percent)	11.00%	11.00%	13.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-42

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 825
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-Section 50
-Paragraph 21
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482907/825-10-50-21

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 825
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 275
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-Section 50
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-URI https://asc.fasb.org//1943274/2147482861/275-10-50-18

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482861/275-10-50-20

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-18

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