Guarantor and Non-Guarantor Subsidiaries Financial Information - Consolidating Statement of Cash Flows Unaudited (Detail) - USD ($) $ in Millions	1 Months Ended		3 Months Ended		9 Months Ended
	Apr. 30, 2018	Mar. 31, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities
Net income			$ 321	$ 143	$ 325	$ 187
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization					205	190
Unrealized losses (gains) and remeasurement of foreign denominated loans					(6)	19
Deferred income taxes					105	(165)
Loss on extinguishment of debt			7	3	31	35
Net (gain) loss on divestitures and investments					(385)	17
Non-cash interest expense					5	6
Equity-based compensation expense					52	26
Changes in operating assets and liabilities:
Accounts receivable					(43)	(55)
Inventories					(1)	2
Royalty advances						(15)
Accounts payable and accrued liabilities					(84)	(55)
Royalty payables					113	152
Accrued interest					(22)	(14)
Deferred revenue						(25)
Other balance sheet changes					(30)	4
Net cash provided (used in) by operating activities					265	309
Cash flows from investing activities
Acquisition of music publishing rights, net					(11)	(11)
Capital expenditures					(40)	(29)
Investments and acquisitions of businesses, net					(14)	(9)
Divestitures, net						43
Proceeds from the sale of investments					516	43
Net cash provided by (used in) investing activities					451	(6)
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp. Senior Term Loan Facility					320	22
Call premiums paid on early redemption of debt					(23)	(27)
Call premiums paid on and redemption deposit for early redemption of debt					(23)
Deferred financing costs paid					(12)	(13)
Distribution to noncontrolling interest holder					(3)	(4)
Dividends paid					(425)	(54)
Net cash used in financing activities					(453)	(97)
Effect of exchange rate changes on cash and equivalents					(5)	2
Net (decrease) increase in cash and equivalents					258	208
Cash and equivalents at beginning of period					647	359
Cash and equivalents at end of period			905	567	905	567
5.50% Senior Notes due 2022
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp					325
Senior Term Loan Facility
Cash flows from financing activities
Proceeds from supplement of Acquisition Corp.					320
6.75% Senior Notes
Adjustments to reconcile net income to net cash provided by operating activities:
Loss on extinguishment of debt	$ 5	$ 23
Cash flows from financing activities
Repayment of redemption deposit					(635)
Repayment of Senior Secured Notes					(635)
4.125% Senior Secured Notes
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp						380
4.875% Senior Secured Notes
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp						250
6.00% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes						(450)
6.25% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes						(173)
5.625% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes						(28)
Reportable Legal Entities | Guarantor Subsidiaries
Cash flows from operating activities
Net income			(30)	175	44	319
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization					101	104
Unrealized losses (gains) and remeasurement of foreign denominated loans					(3)	2
Net (gain) loss on divestitures and investments					84	25
Equity-based compensation expense					52	25
Equity (gains) losses, including distributions					(99)	(53)
Changes in operating assets and liabilities:
Accounts receivable					(39)	(12)
Inventories					(5)	1
Royalty advances						(9)
Accounts payable and accrued liabilities					256	(137)
Royalty payables					32	70
Deferred revenue					30	(42)
Other balance sheet changes					82	(169)
Net cash provided (used in) by operating activities					535	124
Cash flows from investing activities
Acquisition of music publishing rights, net					(7)	(6)
Capital expenditures					(30)	(19)
Investments and acquisitions of businesses, net					(14)	(6)
Divestitures, net						30
Proceeds from the sale of investments					12
Net cash provided by (used in) investing activities					(39)	(1)
Cash flows from financing activities
Dividends paid					(397)	(54)
Change in due to (from) issuer					108	41
Net cash used in financing activities					(289)	(13)
Net (decrease) increase in cash and equivalents					207	110
Cash and equivalents at beginning of period					347	180
Cash and equivalents at end of period			554	290	554	290
Reportable Legal Entities | Non-Guarantor Subsidiaries
Cash flows from operating activities
Net income			39		103	4
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization					104	86
Unrealized losses (gains) and remeasurement of foreign denominated loans					2	2
Deferred income taxes					105	(167)
Net (gain) loss on divestitures and investments					34	(8)
Equity-based compensation expense						1
Changes in operating assets and liabilities:
Accounts receivable					(4)	(43)
Inventories					4	1
Royalty advances						(6)
Accounts payable and accrued liabilities					(189)	(31)
Royalty payables					81	82
Deferred revenue					(30)	17
Other balance sheet changes					(109)	167
Net cash provided (used in) by operating activities					101	105
Cash flows from investing activities
Acquisition of music publishing rights, net					(4)	(5)
Capital expenditures					(10)	(10)
Investments and acquisitions of businesses, net						(3)
Divestitures, net						13
Net cash provided by (used in) investing activities					(14)	(5)
Cash flows from financing activities
Distribution to noncontrolling interest holder					(3)	(4)
Dividends paid					(28)
Net cash used in financing activities					(31)	(4)
Effect of exchange rate changes on cash and equivalents					(5)	2
Net (decrease) increase in cash and equivalents					51	98
Cash and equivalents at beginning of period					300	179
Cash and equivalents at end of period			351	277	351	277
Reportable Legal Entities | Warner Music Group Corp.
Cash flows from operating activities
Net income			320	141	321	182
Adjustments to reconcile net income to net cash provided by operating activities:
Equity (gains) losses, including distributions					(321)	(182)
Reportable Legal Entities | WMG Acquisition Corp.
Cash flows from operating activities
Net income			320	141	321	182
Adjustments to reconcile net income to net cash provided by operating activities:
Unrealized losses (gains) and remeasurement of foreign denominated loans					(5)	15
Deferred income taxes						2
Loss on extinguishment of debt			7	3	31	35
Net (gain) loss on divestitures and investments					(503)
Non-cash interest expense					5	6
Equity (gains) losses, including distributions					(195)	(152)
Changes in operating assets and liabilities:
Accrued interest					(22)	(14)
Other balance sheet changes					(3)	6
Net cash provided (used in) by operating activities					(371)	80
Cash flows from investing activities
Proceeds from the sale of investments					504
Advances from issuer					(108)	(41)
Net cash provided by (used in) investing activities					396	(41)
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp. Senior Term Loan Facility						22
Call premiums paid on early redemption of debt						(27)
Call premiums paid on and redemption deposit for early redemption of debt					(23)
Deferred financing costs paid					(12)	(13)
Net cash used in financing activities					(25)	(39)
Reportable Legal Entities | WMG Acquisition Corp. Consolidated
Cash flows from operating activities
Net income			321	143	325	187
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization					205	190
Unrealized losses (gains) and remeasurement of foreign denominated loans					(6)	19
Deferred income taxes					105	(165)
Loss on extinguishment of debt			7	3	31	35
Net (gain) loss on divestitures and investments					(385)	17
Non-cash interest expense					5	6
Equity-based compensation expense					52	26
Changes in operating assets and liabilities:
Accounts receivable					(43)	(55)
Inventories					(1)	2
Royalty advances						(15)
Accounts payable and accrued liabilities					(84)	(55)
Royalty payables					113	152
Accrued interest					(22)	(14)
Deferred revenue						(25)
Other balance sheet changes					(30)	4
Net cash provided (used in) by operating activities					265	309
Cash flows from investing activities
Acquisition of music publishing rights, net					(11)	(11)
Capital expenditures					(40)	(29)
Investments and acquisitions of businesses, net					(14)	(9)
Divestitures, net						43
Proceeds from the sale of investments					516
Net cash provided by (used in) investing activities					451	(6)
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp. Senior Term Loan Facility						22
Call premiums paid on early redemption of debt						(27)
Call premiums paid on and redemption deposit for early redemption of debt					(23)
Deferred financing costs paid					(12)	(13)
Distribution to noncontrolling interest holder					(3)	(4)
Dividends paid					(425)	(54)
Net cash used in financing activities					(453)	(97)
Effect of exchange rate changes on cash and equivalents					(5)	2
Net (decrease) increase in cash and equivalents					258	208
Cash and equivalents at beginning of period					647	359
Cash and equivalents at end of period			905	567	905	567
Reportable Legal Entities | WMG Holdings Corp.
Cash flows from operating activities
Net income			320	141	321	182
Adjustments to reconcile net income to net cash provided by operating activities:
Equity (gains) losses, including distributions					(321)	(182)
Reportable Legal Entities | 5.50% Senior Notes due 2022 | WMG Acquisition Corp.
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp					325
Reportable Legal Entities | 5.50% Senior Notes due 2022 | WMG Acquisition Corp. Consolidated
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp					325
Reportable Legal Entities | Senior Term Loan Facility | WMG Acquisition Corp.
Cash flows from financing activities
Proceeds from supplement of Acquisition Corp.					320
Reportable Legal Entities | Senior Term Loan Facility | WMG Acquisition Corp. Consolidated
Cash flows from financing activities
Proceeds from supplement of Acquisition Corp.					320
Reportable Legal Entities | 6.75% Senior Notes | WMG Acquisition Corp.
Cash flows from financing activities
Repayment of redemption deposit					(635)
Reportable Legal Entities | 6.75% Senior Notes | WMG Acquisition Corp. Consolidated
Cash flows from financing activities
Repayment of redemption deposit					(635)
Reportable Legal Entities | 4.125% Senior Secured Notes | WMG Acquisition Corp.
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp						380
Reportable Legal Entities | 4.125% Senior Secured Notes | WMG Acquisition Corp. Consolidated
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp						380
Reportable Legal Entities | 4.875% Senior Secured Notes | WMG Acquisition Corp.
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp						250
Reportable Legal Entities | 4.875% Senior Secured Notes | WMG Acquisition Corp. Consolidated
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp						250
Reportable Legal Entities | 6.00% Senior Secured Notes | WMG Acquisition Corp.
Cash flows from financing activities
Repayment of Senior Secured Notes						(450)
Reportable Legal Entities | 6.00% Senior Secured Notes | WMG Acquisition Corp. Consolidated
Cash flows from financing activities
Repayment of Senior Secured Notes						(450)
Reportable Legal Entities | 6.25% Senior Secured Notes | WMG Acquisition Corp.
Cash flows from financing activities
Repayment of Senior Secured Notes						(173)
Reportable Legal Entities | 6.25% Senior Secured Notes | WMG Acquisition Corp. Consolidated
Cash flows from financing activities
Repayment of Senior Secured Notes						(173)
Reportable Legal Entities | 5.625% Senior Secured Notes | WMG Acquisition Corp.
Cash flows from financing activities
Repayment of Senior Secured Notes						(28)
Reportable Legal Entities | 5.625% Senior Secured Notes | WMG Acquisition Corp. Consolidated
Cash flows from financing activities
Repayment of Senior Secured Notes						(28)
Eliminations
Cash flows from operating activities
Net income			(640)	(282)	(642)	(364)
Adjustments to reconcile net income to net cash provided by operating activities:
Equity (gains) losses, including distributions					642	364
Eliminations | WMG Acquisition Corp.
Cash flows from operating activities
Net income			$ (8)	$ (173)	(143)	(318)
Adjustments to reconcile net income to net cash provided by operating activities:
Equity (gains) losses, including distributions					294	205
Changes in operating assets and liabilities:
Accounts payable and accrued liabilities					(151)	113
Cash flows from investing activities
Advances from issuer					108	41
Net cash provided by (used in) investing activities					108	41
Cash flows from financing activities
Change in due to (from) issuer					(108)	(41)
Net cash used in financing activities					$ (108)	$ (41)