Goodwill and Intangible Assets - Schedule of Intangible Assets (Detail) - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2019	Sep. 30, 2018
Finite Lived And Indefinite Lived Intangible Assets [Line Items]
Total gross intangible asset subject to amortization	$ 3,361	$ 3,312
Accumulated amortization	(1,559)	(1,461)
Total net intangible assets subject to amortization	1,802	1,851
Intangible assets not subject to amortization	153	154
Total net intangible assets	1,955	2,005
Trademarks and tradenames
Finite Lived And Indefinite Lived Intangible Assets [Line Items]
Intangible assets not subject to amortization	$ 153	154
Recorded music catalog
Finite Lived And Indefinite Lived Intangible Assets [Line Items]
Intangible assets, Useful Life	10 years
Total gross intangible asset subject to amortization	$ 864	870
Music publishing copyrights
Finite Lived And Indefinite Lived Intangible Assets [Line Items]
Intangible assets, Useful Life	26 years
Total gross intangible asset subject to amortization	$ 1,546	1,540
Artist and songwriter contracts
Finite Lived And Indefinite Lived Intangible Assets [Line Items]
Intangible assets, Useful Life	13 years
Total gross intangible asset subject to amortization	$ 858	864
Trademarks
Finite Lived And Indefinite Lived Intangible Assets [Line Items]
Intangible assets, Useful Life	6 years
Total gross intangible asset subject to amortization	$ 12	12
Other Intangible Assets
Finite Lived And Indefinite Lived Intangible Assets [Line Items]
Intangible assets, Useful Life	5 years
Total gross intangible asset subject to amortization	$ 81	$ 26