Quarterly Financial Information - Quarterly Information (Detail) - USD ($) $ in Millions	3 Months Ended																12 Months Ended
	Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2015		Sep. 30, 2014		Sep. 30, 2013
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 750		$ 710		$ 677		$ 829		$ 771		$ 788		$ 653		$ 815		$ 2,966		$ 3,027		$ 2,871
Costs and expenses:
Cost of revenue	(375)		(373)		(318)		(445)		(393)		(417)		(319)		(441)		(1,511)		(1,570)		(1,492)
Selling, general and administrative expenses	(274)	[1]	(251)	[1]	(252)	[1]	(296)	[1]	(287)	[2]	(319)	[2]	(273)	[2]	(293)	[2]	(1,073)	[3]	(1,172)	[3]	(1,097)	[3]
Amortization expense	(64)		(63)		(63)		(65)		(67)		(67)		(66)		(66)		(255)		(266)		(207)
Total costs and expenses	(713)		(687)		(633)		(806)		(747)		(803)		(658)		(800)		(2,839)		(3,008)		(2,796)
Operating income	37		23		44		23		24		(15)		(5)		15		127		19		75
Loss on extinguishment of debt											(141)								(141)		(85)
Interest expense, net	(45)		(45)		(45)		(46)		(46)		(48)		(54)		(55)		(181)		(203)		(203)
Other income (expense)	(9)		(17)		14		(9)		(1)		4		(3)		(4)		(21)		(4)		(12)
Loss before income taxes	(17)		(39)		13		(32)		(23)		(200)		(62)		(44)		(75)		(329)		(225)
Income tax (expense) benefit	(6)		(4)		6		(9)		(1)		16		3		8		(13)		26		31
Net (loss) income	(23)		(43)		19		(41)		(24)		(184)		(59)		(36)		(88)		(303)		(194)
Less: Income attributable to noncontrolling interest			(1)		(1)		(1)		(2)		(1)		(1)		(1)		(3)		(5)		(4)
Net loss attributable to Warner Music Group Corp.	$ (23)		$ (44)		$ 18		$ (42)		$ (26)		$ (185)		$ (60)		$ (37)		$ (91)		$ (308)		$ (198)

[1] (a) Includes depreciation expense of: $(12) $(14) $(14) $(14)

[2] (a) Includes depreciation expense of: $(16) $(14) $(13) $(12)

[3] (a) Includes depreciation expense of: $(54) $(55) $(51)