Consolidated Statement of (Deficit) Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	Total Warner Music Group Corp. Deficit	Noncontrolling Interest
Beginning balance (in shares) at Sep. 30, 2017		1,055
Beginning balance at Sep. 30, 2017	$ 308	$ 0	$ 1,128	$ (654)	$ (181)	$ 293	$ 15
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	325			321		321	4
Other comprehensive income (loss), net of tax	(14)				(14)	(14)
Dividends	(425)			(425)		(425)
Distribution to noncontrolling interest holders	(3)						(3)
Other (in shares)		(3)
Ending balance (in shares) at Jun. 30, 2018		1,052
Ending balance at Jun. 30, 2018	191	$ 0	1,128	(758)	(195)	175	16
Beginning balance (in shares) at Mar. 31, 2018		1,052
Beginning balance at Mar. 31, 2018	205	$ 0	1,128	(778)	(161)	189	16
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	321			320		320	1
Other comprehensive income (loss), net of tax	(34)				(34)	(34)
Dividends	(300)			(300)		(300)
Distribution to noncontrolling interest holders	(1)						(1)
Ending balance (in shares) at Jun. 30, 2018		1,052
Ending balance at Jun. 30, 2018	$ 191	$ 0	1,128	(758)	(195)	175	16
Beginning balance (in shares) at Sep. 30, 2018	1,052	1,052
Beginning balance at Sep. 30, 2018	$ (320)	$ 0	1,128	(1,272)	(190)	(334)	14
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of ASC 606 adoption	150			139		139	11
Net income	167			166		166	1
Other comprehensive income (loss), net of tax	(29)				(29)	(29)
Dividends	(94)			(94)		(94)
Distribution to noncontrolling interest holders	(3)						(3)
Other (in shares)		8
Other	$ (4)						(4)
Ending balance (in shares) at Jun. 30, 2019	1,052	1,060
Ending balance at Jun. 30, 2019	$ (133)	$ 0	1,128	(1,061)	(219)	(152)	19
Beginning balance (in shares) at Mar. 31, 2019		1,060
Beginning balance at Mar. 31, 2019	(120)	$ 0	1,128	(1,043)	(225)	(140)	20
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	14			13		13	1
Other comprehensive income (loss), net of tax	6				6	6
Dividends	(31)			(31)		(31)
Distribution to noncontrolling interest holders	(1)						(1)
Other	$ (1)						(1)
Ending balance (in shares) at Jun. 30, 2019	1,052	1,060
Ending balance at Jun. 30, 2019	$ (133)	$ 0	$ 1,128	$ (1,061)	$ (219)	$ (152)	$ 19