Segment Information - Narrative (Details)	12 Months Ended
	Sep. 30, 2024 customer segment	Sep. 30, 2023 customer	Sep. 30, 2022 customer
Segment Reporting Information [Line Items]
Number of fundamental operations | segment	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%	18.00%	17.00%
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%	12.00%
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%	11.00%