Consolidated Statements of Equity - USD ($) $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	Class A Common Stock	Class B Common Stock	Total Warner Music Group Corp. Equity (Deficit)	Total Warner Music Group Corp. Equity (Deficit) Cumulative Effect, Period of Adoption, Adjustment	Common Stock Class A Common Stock	Common Stock Class B Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Loss	Non-controlling Interest
Beginning balance (in shares) at Sep. 30, 2022							137,199,000	377,650,000
Beginning balance at Sep. 30, 2022	$ 168				$ 152		$ 0	$ 1	$ 1,975	$ (1,477)		$ (347)	$ 16
Beginning balance (Accounting Standards Update 2016-02) at Sep. 30, 2022		$ 0				$ 0					$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	439				430					430			9
Other comprehensive (loss) income, net of tax	25				25							25
Dividends	(340)				(340)					(340)
Stock-based compensation expense	39				39				39
Distribution to noncontrolling interest holders	(12)												(12)
Conversion of Class B shares to Class A shares (in shares)							0	0
Acquisition of noncontrolling interests	112												112
Shares issued under the plan (in shares)							869,000
Shares issued under Omnibus incentive plan (in shares)			276,516				277,000
Other	(1)				1				1				(2)
Ending balance (in shares) at Sep. 30, 2023							138,345,000	377,650,000
Ending balance at Sep. 30, 2023	430				307		$ 0	$ 1	2,015	(1,387)		(322)	123
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	478				435					435			43
Other comprehensive (loss) income, net of tax	75				75							75
Dividends	(361)				(361)					(361)
Stock-based compensation expense	67				67				67
Distribution to noncontrolling interest holders	(8)												(8)
Acquisition of noncontrolling interests	(1)												(1)
Shares issued under the plan (in shares)							1,738,016	2,270,136
Exchange of Class B shares for Class A shares (in shares)							2,270,000	2,270,000
Shares issued under Omnibus incentive plan (in shares)			206,298				206,000
Shares issued under Omnibus Incentive Plan	(5)				(5)				(5)
Other	0				0				0				0
Ending balance (in shares) at Sep. 30, 2024			142,559,000	375,380,000			142,559,000	375,380,000
Ending balance at Sep. 30, 2024	675				518		$ 0	$ 1	2,077	(1,313)		(247)	157
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	370				365					365			5
Other comprehensive (loss) income, net of tax	58				58							58
Dividends	(383)				(383)					(383)
Stock-based compensation expense	61				61				61
Distribution to noncontrolling interest holders	(15)												(15)
Vesting of restricted stock units, net of shares withheld for employee taxes (in shares)							800,000
Vesting of restricted stock units, net of shares withheld for employee taxes	(20)				(20)				(20)
Acquisition of noncontrolling interests	74												74
Shares issued under the plan (in shares)							2,607,027
Shares issued under Omnibus incentive plan (in shares)			799,748
Common shares repurchased and retired (in shares)							(477,000)
Common shares repurchased and retired	(16)				(16)				(16)
Redemption of noncontrolling interests (in shares)							1,417,000
Redemption of noncontrolling interests	(47)				64				64				(111)
Ending balance (in shares) at Sep. 30, 2025			146,906,000	375,380,000			146,906,000	375,380,000
Ending balance at Sep. 30, 2025	$ 757				$ 647		$ 0	$ 1	$ 2,166	$ (1,331)		$ (189)	$ 110