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Related Party Transactions - Additional Information (Details)			12 Months Ended
	Aug. 13, 2015 USD ($)	Jan. 01, 2015 GBP (£)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Oct. 01, 2018 USD ($) shares
Related Party Transaction [Line Items]
Remaining lease term			8 years
Extended lease term			10 years
Licensing Agreements
Related Party Transaction [Line Items]
Finite-lived intangible asset, useful life			24 months
Access Industries
Related Party Transaction [Line Items]
Management fees and reimbursed expenses			$ 7,000,000	$ 11,000,000	$ 16,000,000
Warner Music Inc
Related Party Transaction [Line Items]
IT support fee	$ 1,000
Warner Music Inc \| License fee
Related Party Transaction [Line Items]
License fee	$ 2,775
Warner and Chappell Music Limited and WMG Acquisition Limited
Related Party Transaction [Line Items]
Payments for rent \| £		£ 3,460,250
Extended lease term		5 years
Snap, Inc. \| Licensing Agreements
Related Party Transaction [Line Items]
Finite-lived intangible asset, useful life			2 years
Related party revenue			$ 500,000,000
Mattel Inc. \| Distribution Agreements
Related Party Transaction [Line Items]
Finite-lived intangible asset, useful life			3 years
Related party revenue			$ 200,000,000
WMG China
Related Party Transaction [Line Items]
Ownership percentage						20.00%
WMG China \| AI New Holdings 5 LLC
Related Party Transaction [Line Items]
Noncontrolling interest, ownership percentage by parent						80.00%
WMG China \| Tencent Music Entertainment Group
Related Party Transaction [Line Items]
Purchase of ordinary shares (in shares) \| shares						37,162,288
Purchase of ordinary shares, value						$ 100,000,000
Building
Related Party Transaction [Line Items]
Related party transactions, annual rent payments			$ 13,000,000
Remaining lease term			10 years
Extended lease term			10 years
Streaming Service License \| Deezer
Related Party Transaction [Line Items]
Related party revenue			$ 42,000,000	49,000,000	$ 39,000,000
PEDL And Latin America Licenses \| Deezer
Related Party Transaction [Line Items]
Related party revenue			2,000,000	$ 1,000,000
One-Time Termination Fee \| Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			$ 60,000,000