Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Numerator
Net income attributable to Warner Music Group Corp.	$ 435	$ 430	$ 551
Class A
Numerator
Net income attributable to Warner Music Group Corp.	122	119	149
Less: Net income attributable to participating securities	(6)	(6)	(7)
Net income attributable to common stockholders	$ 116	$ 113	$ 142
Denominator
Weighted average shares outstanding, basic (in shares)	140,882,000	138,070,000	133,662,000
Weighted average shares outstanding, diluted (in shares)	140,882,000	138,070,000	133,662,000
Basic EPS (in dollars per share)	$ 0.83	$ 0.82	$ 1.06
Diluted EPS (in dollars per share)	$ 0.83	$ 0.82	$ 1.06
Class B
Numerator
Net income attributable to Warner Music Group Corp.	$ 313	$ 311	$ 402
Less: Net income attributable to participating securities	0	0	0
Net income attributable to common stockholders	$ 313	$ 311	$ 402
Denominator
Weighted average shares outstanding, basic (in shares)	376,641,000	377,650,000	381,046,000
Weighted average shares outstanding, diluted (in shares)	376,641,000	377,650,000	381,046,000
Basic EPS (in dollars per share)	$ 0.83	$ 0.82	$ 1.06
Diluted EPS (in dollars per share)	$ 0.83	$ 0.82	$ 1.06