Consolidated Statements of Operations - USD ($) $ in Millions	3 Months Ended																12 Months Ended
	Sep. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2015		Sep. 30, 2017		Sep. 30, 2016		Sep. 30, 2015
Income Statement [Abstract]
Revenues	$ 917		$ 917		$ 825		$ 917		$ 841		$ 811		$ 745		$ 849		$ 3,576		$ 3,246		$ 2,966
Costs and expenses:
Cost of revenue	(501)		(519)		(415)		(496)		(436)		(448)		(374)		(449)		(1,931)		(1,707)		(1,511)
Selling, general and administrative expenses	(368)	[1]	(296)	[1]	(282)	[1]	(276)	[1]	(295)	[2]	(255)	[2]	(256)	[2]	(276)	[2]	(1,222)	[3]	(1,082)	[3]	(1,073)	[3]
Amortization expense	(49)		(51)		(50)		(51)		(55)		(63)		(63)		(62)		(201)		(243)		(255)
Total costs and expenses	(918)		(866)		(747)		(823)		(786)		(766)		(693)		(787)		(3,354)		(3,032)		(2,839)
Operating income	(1)		51		78		94		55		45		52		62		222		214		127
Loss on extinguishment of debt			(3)				(32)		(14)				(4)				(35)		(18)
Interest expense, net	(37)		(36)		(36)		(40)		(42)		(43)		(43)		(45)		(149)		(173)		(181)
Other (expense) income	(19)		(21)		(19)		19		(7)		(5)		22		8		(40)		18		(21)
(Loss) income before income taxes	(57)		(9)		23		41		(8)		(3)		27		25		(2)		41		(75)
Income tax benefit (expense)	19		152		(3)		(17)		5		(4)		(15)		3		151		(11)		(13)
Net income (loss)																	149		30		(88)
Less: Income attributable to noncontrolling interest	(1)		(2)		(1)		(2)		(1)		(2)		(1)		(1)		(6)		(5)		(3)
Net income (loss) attributable to Warner Music Group Corp.	$ (39)		$ 141		$ 19		$ 22		$ (4)		$ (9)		$ 11		$ 27		$ 143		$ 25		$ (91)

[1] (a) Includes depreciation expense of: $(12) $(13) $(13) $(12)

[2] (a) Includes depreciation expense of: $(13) $(12) $(12) $(13)

[3] (a) Includes depreciation expense of: $(50) $(50) $(54)