Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 67	$ (1)	$ 153	$ 4
Other comprehensive (loss) income, net of tax:
Foreign currency adjustment	(10)	9	(26)	18
Deferred (loss) gain on derivative	(3)	1	(9)	2
Other comprehensive (loss) income, net of tax	(13)	10	(35)	20
Total comprehensive income	54	9	118	24
Less: Income attributable to noncontrolling interest		(2)		(3)
Comprehensive income attributable to Warner Music Group Corp.	$ 54	$ 7	$ 118	$ 21