Guarantor and Non-Guarantor Subsidiaries Financial Information - Consolidating Statement of Operations Unaudited (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2016
Condensed Income Statements Captions [Line Items]
Revenues		$ 1,045	$ 917
Costs and expenses:
Cost of revenue		(569)	(496)
Selling, general and administrative expenses	[1]	(333)	(276)
Amortization expense		(53)	(51)
Total costs and expenses		(955)	(823)
Operating income		90	94
Loss on extinguishment of debt		(1)	(32)	$ (32)
Interest (expense) income, net		(36)	(40)
Equity gains (losses) from equity method investments		1
Other income, net		3	19
Income before income taxes		57	41
Income tax (expense) benefit		(52)	(17)
Net income		5	24	24
Less: Income attributable to noncontrolling interest		(1)	(2)
Net income attributable to Warner Music Group Corp.		4	22
Reportable Legal Entities | Guarantor Subsidiaries
Condensed Income Statements Captions [Line Items]
Revenues		547	490
Costs and expenses:
Cost of revenue		(257)	(220)
Selling, general and administrative expenses		(235)	(176)
Amortization expense		(24)	(25)
Total costs and expenses		(516)	(421)
Operating income		31	69
Interest (expense) income, net		1	1
Equity gains (losses) from equity method investments		44	40
Other income, net		9	3
Income before income taxes		85	113
Income tax (expense) benefit		(51)	(18)
Net income		34	95	95
Net income attributable to Warner Music Group Corp.		34	95
Reportable Legal Entities | Non-Guarantor Subsidiaries
Condensed Income Statements Captions [Line Items]
Revenues		621	521
Costs and expenses:
Cost of revenue		(393)	(341)
Selling, general and administrative expenses		(138)	(128)
Amortization expense		(29)	(26)
Total costs and expenses		(560)	(495)
Operating income		61	26
Interest (expense) income, net		(8)	(18)
Other income, net		(2)	4
Income before income taxes		51	12
Income tax (expense) benefit		(10)	(9)
Net income		41	3	3
Less: Income attributable to noncontrolling interest		(1)	(2)
Net income attributable to Warner Music Group Corp.		40	1
Reportable Legal Entities | Warner Music Group Corp.
Costs and expenses:
Equity gains (losses) from equity method investments		4	22
Income before income taxes		4	22
Net income		4	22	22
Net income attributable to Warner Music Group Corp.		4	22
Reportable Legal Entities | WMG Acquisition Corp.
Costs and expenses:
Selling, general and administrative expenses			(1)
Total costs and expenses			(1)
Operating income			(1)
Loss on extinguishment of debt		(1)	(32)	(32)
Interest (expense) income, net		(29)	(23)
Equity gains (losses) from equity method investments		90	83
Other income, net		(4)	12
Income before income taxes		56	39
Income tax (expense) benefit		(52)	(17)
Net income		4	22	22
Net income attributable to Warner Music Group Corp.		4	22
Reportable Legal Entities | WMG Acquisition Corp. Consolidated
Condensed Income Statements Captions [Line Items]
Revenues		1,045	917
Costs and expenses:
Cost of revenue		(569)	(496)
Selling, general and administrative expenses		(333)	(276)
Amortization expense		(53)	(51)
Total costs and expenses		(955)	(823)
Operating income		90	94
Loss on extinguishment of debt		(1)	(32)	(32)
Interest (expense) income, net		(36)	(40)
Equity gains (losses) from equity method investments		1
Other income, net		3	19
Income before income taxes		57	41
Income tax (expense) benefit		(52)	(17)
Net income		5	24	24
Less: Income attributable to noncontrolling interest		(1)	(2)
Net income attributable to Warner Music Group Corp.		4	22
Reportable Legal Entities | WMG Holdings Corp.
Costs and expenses:
Equity gains (losses) from equity method investments		4	22
Income before income taxes		4	22
Net income		4	22	22
Net income attributable to Warner Music Group Corp.		4	22
Eliminations
Costs and expenses:
Equity gains (losses) from equity method investments		(8)	(44)
Income before income taxes		(8)	(44)
Net income		(8)	(44)	(44)
Net income attributable to Warner Music Group Corp.		(8)	(44)
Eliminations | WMG Acquisition Corp.
Condensed Income Statements Captions [Line Items]
Revenues		(123)	(94)
Costs and expenses:
Cost of revenue		81	65
Selling, general and administrative expenses		40	29
Total costs and expenses		121	94
Operating income		(2)
Equity gains (losses) from equity method investments		(133)	(123)
Income before income taxes		(135)	(123)
Income tax (expense) benefit		61	27
Net income		(74)	(96)	$ (96)
Net income attributable to Warner Music Group Corp.		$ (74)	$ (96)

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