Guarantor and Non-Guarantor Subsidiaries Financial Information - Consolidating Statement of Comprehensive Income Unaudited (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2016
Condensed Statement Of Income Captions [Line Items]
Net income	$ 5	$ 24	$ 24
Other comprehensive income (loss), net of tax:
Foreign currency adjustment	9	(37)
Deferred gains (losses) on derivative financial instruments	1	(2)
Other comprehensive income (loss), net of tax	10	(39)
Total comprehensive income (loss)	15	(15)
Less: Income attributable to noncontrolling interest	(1)	(2)
Comprehensive income (loss) attributable to Warner Music Group Corp.	14	(17)
Reportable Legal Entities | Guarantor Subsidiaries
Condensed Statement Of Income Captions [Line Items]
Net income	34	95	95
Other comprehensive income (loss), net of tax:
Deferred gains (losses) on derivative financial instruments		(2)
Other comprehensive income (loss), net of tax		(2)
Total comprehensive income (loss)	34	93
Comprehensive income (loss) attributable to Warner Music Group Corp.	34	93
Reportable Legal Entities | Non-Guarantor Subsidiaries
Condensed Statement Of Income Captions [Line Items]
Net income	41	3	3
Other comprehensive income (loss), net of tax:
Foreign currency adjustment	(9)	37
Deferred gains (losses) on derivative financial instruments	(1)
Other comprehensive income (loss), net of tax	(10)	37
Total comprehensive income (loss)	31	40
Less: Income attributable to noncontrolling interest	(1)	(2)
Comprehensive income (loss) attributable to Warner Music Group Corp.	30	38
Reportable Legal Entities | Warner Music Group Corp.
Condensed Statement Of Income Captions [Line Items]
Net income	4	22	22
Other comprehensive income (loss), net of tax:
Foreign currency adjustment	9	(37)
Deferred gains (losses) on derivative financial instruments	1	(2)
Other comprehensive income (loss), net of tax	10	(39)
Total comprehensive income (loss)	14	(17)
Comprehensive income (loss) attributable to Warner Music Group Corp.	14	(17)
Reportable Legal Entities | WMG Acquisition Corp.
Condensed Statement Of Income Captions [Line Items]
Net income	4	22	22
Other comprehensive income (loss), net of tax:
Foreign currency adjustment	9	(37)
Deferred gains (losses) on derivative financial instruments	1	(2)
Other comprehensive income (loss), net of tax	10	(39)
Total comprehensive income (loss)	14	(17)
Comprehensive income (loss) attributable to Warner Music Group Corp.	14	(17)
Reportable Legal Entities | WMG Acquisition Corp. Consolidated
Condensed Statement Of Income Captions [Line Items]
Net income	5	24	24
Other comprehensive income (loss), net of tax:
Foreign currency adjustment	9	(37)
Deferred gains (losses) on derivative financial instruments	1	(2)
Other comprehensive income (loss), net of tax	10	(39)
Total comprehensive income (loss)	15	(15)
Less: Income attributable to noncontrolling interest	(1)	(2)
Comprehensive income (loss) attributable to Warner Music Group Corp.	14	(17)
Reportable Legal Entities | WMG Holdings Corp.
Condensed Statement Of Income Captions [Line Items]
Net income	4	22	22
Other comprehensive income (loss), net of tax:
Foreign currency adjustment	9	(37)
Deferred gains (losses) on derivative financial instruments	1	(2)
Other comprehensive income (loss), net of tax	10	(39)
Total comprehensive income (loss)	14	(17)
Comprehensive income (loss) attributable to Warner Music Group Corp.	14	(17)
Eliminations
Condensed Statement Of Income Captions [Line Items]
Net income	(8)	(44)	(44)
Other comprehensive income (loss), net of tax:
Foreign currency adjustment	(18)	74
Deferred gains (losses) on derivative financial instruments	(2)	4
Other comprehensive income (loss), net of tax	(20)	78
Total comprehensive income (loss)	(28)	34
Comprehensive income (loss) attributable to Warner Music Group Corp.	(28)	34
Eliminations | WMG Acquisition Corp.
Condensed Statement Of Income Captions [Line Items]
Net income	(74)	(96)	$ (96)
Other comprehensive income (loss), net of tax:
Foreign currency adjustment	9	(37)
Deferred gains (losses) on derivative financial instruments	1	2
Other comprehensive income (loss), net of tax	10	(35)
Total comprehensive income (loss)	(64)	(131)
Comprehensive income (loss) attributable to Warner Music Group Corp.	$ (64)	$ (131)