Guarantor and Non-Guarantor Subsidiaries Financial Information - Consolidating Statement of Cash Flows Unaudited (Detail) - USD ($) $ in Millions				3 Months Ended		12 Months Ended
	Nov. 05, 2018	Oct. 12, 2018	Oct. 09, 2018	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2019
Cash flows from operating activities
Net income				$ 122	$ 86
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization				71	68
Unrealized gains and remeasurement of foreign-denominated loans				5	(13)
Deferred income taxes				(29)	11
Loss on extinguishment of debt				0	3
Net gain on divestitures and investments				1	(15)
Non-cash interest expense				1	2
Equity-based compensation expense				(7)	12
Equity gains, including distributions				0	0
Changes in operating assets and liabilities:
Accounts receivable, net				(101)	(88)
Inventories				10	13
Royalty advances				(38)	(28)
Accounts payable and accrued liabilities				(44)	(92)
Royalty payables				84	92
Accrued interest				(11)	(7)
Operating lease liabilities				1	0
Deferred revenue				(21)	(5)
Other balance sheet changes				34	53
Net cash provided by operating activities				78	92
Cash flows from investing activities
Acquisition of music publishing rights, net				(11)	(5)
Capital expenditures				(15)	(26)
Investments and acquisitions of businesses, net				(6)	(207)
Proceeds from the sale of investments					0
Advances from issuer				0	0
Net cash used in investing activities				(32)	(238)
Cash flows from financing activities
Dividend by Acquisition Corp. to Holdings Corp.				(206)	0
Call premiums paid and deposit on early redemption of debt				0	(2)
Deferred financing costs paid				0	(4)
Distribution to noncontrolling interest holder				(1)	(2)
Dividends paid					0
Change in due to (from) issuer				0	0
Net cash (used in) provided by financing activities				(207)	182
Effect of exchange rate changes on cash and equivalents				4	(2)
Net (decrease) increase in cash and equivalents				(157)	34
Cash and equivalents at beginning of period				619	514	$ 514
Cash and equivalents at end of period				462	548	619
3.625% Senior Secured Notes
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp				0	287
4.125% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes				0	(40)
4.875% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes				0	(30)
5.625% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes				0	(27)
WMG Acquisition Corp. | 4.125% Senior Secured Notes
Adjustments to reconcile net income to net cash provided by operating activities:
Loss on extinguishment of debt		$ 2
WMG Acquisition Corp. | 4.875% Senior Secured Notes
Adjustments to reconcile net income to net cash provided by operating activities:
Loss on extinguishment of debt			$ 1
WMG Acquisition Corp. | 5.625% Senior Secured Notes
Adjustments to reconcile net income to net cash provided by operating activities:
Loss on extinguishment of debt	$ 1					4
Reportable Legal Entities | Guarantor Subsidiaries
Cash flows from operating activities
Net income				154	128
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization				43	34
Unrealized gains and remeasurement of foreign-denominated loans				2	(4)
Deferred income taxes				0	0
Loss on extinguishment of debt					0
Net gain on divestitures and investments				1	(15)
Non-cash interest expense				0	0
Equity-based compensation expense				(7)	12
Equity gains, including distributions				(86)	(109)
Changes in operating assets and liabilities:
Accounts receivable, net				(57)	(3)
Inventories				(1)	2
Royalty advances				(16)	(15)
Accounts payable and accrued liabilities				92	64
Royalty payables				(38)	(91)
Accrued interest				0	0
Operating lease liabilities				1
Deferred revenue				(6)	3
Other balance sheet changes				(27)	24
Net cash provided by operating activities				55	30
Cash flows from investing activities
Acquisition of music publishing rights, net				(8)	(4)
Capital expenditures				(8)	(22)
Investments and acquisitions of businesses, net				(2)	(23)
Proceeds from the sale of investments					0
Advances from issuer				0	0
Net cash used in investing activities				(18)	(49)
Cash flows from financing activities
Dividend by Acquisition Corp. to Holdings Corp.				(206)
Call premiums paid and deposit on early redemption of debt					0
Deferred financing costs paid					0
Distribution to noncontrolling interest holder				0	(1)
Dividends paid					0
Change in due to (from) issuer				(33)	84
Net cash (used in) provided by financing activities				(239)	83
Effect of exchange rate changes on cash and equivalents				0	0
Net (decrease) increase in cash and equivalents				(202)	64
Cash and equivalents at beginning of period				386	169	169
Cash and equivalents at end of period				184	233	386
Reportable Legal Entities | Guarantor Subsidiaries | 3.625% Senior Secured Notes
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp					0
Reportable Legal Entities | Guarantor Subsidiaries | 4.125% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					0
Reportable Legal Entities | Guarantor Subsidiaries | 4.875% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					0
Reportable Legal Entities | Guarantor Subsidiaries | 5.625% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					0
Reportable Legal Entities | Non-Guarantor Subsidiaries
Cash flows from operating activities
Net income				64	84
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization				28	34
Unrealized gains and remeasurement of foreign-denominated loans				(9)	0
Deferred income taxes				(29)	11
Loss on extinguishment of debt					0
Net gain on divestitures and investments				0	0
Non-cash interest expense				0	0
Equity-based compensation expense				0	0
Equity gains, including distributions				0	0
Changes in operating assets and liabilities:
Accounts receivable, net				(44)	(85)
Inventories				11	11
Royalty advances				(22)	(13)
Accounts payable and accrued liabilities				(112)	(86)
Royalty payables				122	183
Accrued interest				0	0
Operating lease liabilities				0
Deferred revenue				(15)	(8)
Other balance sheet changes				62	25
Net cash provided by operating activities				56	156
Cash flows from investing activities
Acquisition of music publishing rights, net				(3)	(1)
Capital expenditures				(7)	(4)
Investments and acquisitions of businesses, net				(4)	(184)
Proceeds from the sale of investments					0
Advances from issuer				0	0
Net cash used in investing activities				(14)	(189)
Cash flows from financing activities
Dividend by Acquisition Corp. to Holdings Corp.				0
Call premiums paid and deposit on early redemption of debt					0
Deferred financing costs paid					0
Distribution to noncontrolling interest holder				(1)	(1)
Dividends paid					0
Change in due to (from) issuer				0	0
Net cash (used in) provided by financing activities				(1)	(1)
Effect of exchange rate changes on cash and equivalents				4	(2)
Net (decrease) increase in cash and equivalents				45	(36)
Cash and equivalents at beginning of period				233	345	345
Cash and equivalents at end of period				278	309	233
Reportable Legal Entities | Non-Guarantor Subsidiaries | 3.625% Senior Secured Notes
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp					0
Reportable Legal Entities | Non-Guarantor Subsidiaries | 4.125% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					0
Reportable Legal Entities | Non-Guarantor Subsidiaries | 4.875% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					0
Reportable Legal Entities | Non-Guarantor Subsidiaries | 5.625% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					0
Reportable Legal Entities | Warner Music Group Corp.
Cash flows from operating activities
Net income				120	86
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization				0	0
Unrealized gains and remeasurement of foreign-denominated loans				0	0
Deferred income taxes				0	0
Loss on extinguishment of debt					0
Net gain on divestitures and investments				0	0
Non-cash interest expense				0	0
Equity-based compensation expense				0	0
Equity gains, including distributions				(120)	(86)
Changes in operating assets and liabilities:
Accounts receivable, net				0	0
Inventories				0	0
Royalty advances				0	0
Accounts payable and accrued liabilities				0	0
Royalty payables				0	0
Accrued interest				0	0
Operating lease liabilities				0
Deferred revenue				0	0
Other balance sheet changes				0	0
Net cash provided by operating activities				0	0
Cash flows from investing activities
Acquisition of music publishing rights, net				0	0
Capital expenditures				0	0
Investments and acquisitions of businesses, net				0	0
Proceeds from the sale of investments					0
Advances from issuer				0	0
Net cash used in investing activities				0	0
Cash flows from financing activities
Dividend by Acquisition Corp. to Holdings Corp.				0
Call premiums paid and deposit on early redemption of debt					0
Deferred financing costs paid					0
Distribution to noncontrolling interest holder				0	0
Dividends paid					0
Change in due to (from) issuer				0	0
Net cash (used in) provided by financing activities				0	0
Effect of exchange rate changes on cash and equivalents				0	0
Net (decrease) increase in cash and equivalents				0	0
Cash and equivalents at beginning of period				0	0	0
Cash and equivalents at end of period				0	0	0
Reportable Legal Entities | Warner Music Group Corp. | 3.625% Senior Secured Notes
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp					0
Reportable Legal Entities | Warner Music Group Corp. | 4.125% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					0
Reportable Legal Entities | Warner Music Group Corp. | 4.875% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					0
Reportable Legal Entities | Warner Music Group Corp. | 5.625% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					0
Reportable Legal Entities | WMG Acquisition Corp.
Cash flows from operating activities
Net income				120	86
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization				0	0
Unrealized gains and remeasurement of foreign-denominated loans				12	(10)
Deferred income taxes				0	0
Loss on extinguishment of debt					3
Net gain on divestitures and investments				0	0
Non-cash interest expense				1	2
Equity-based compensation expense				0	0
Equity gains, including distributions				(154)	(172)
Changes in operating assets and liabilities:
Accounts receivable, net				0	0
Inventories				0	0
Royalty advances				0	0
Accounts payable and accrued liabilities				0	0
Royalty payables				0	0
Accrued interest				(11)	(7)
Operating lease liabilities				0
Deferred revenue				0	0
Other balance sheet changes				(1)	4
Net cash provided by operating activities				(33)	(94)
Cash flows from investing activities
Acquisition of music publishing rights, net				0	0
Capital expenditures				0	0
Investments and acquisitions of businesses, net				0	0
Proceeds from the sale of investments					0
Advances from issuer				33	(84)
Net cash used in investing activities				33	(84)
Cash flows from financing activities
Dividend by Acquisition Corp. to Holdings Corp.				0
Call premiums paid and deposit on early redemption of debt					(2)
Deferred financing costs paid					(4)
Distribution to noncontrolling interest holder				0	0
Dividends paid					0
Change in due to (from) issuer				0	0
Net cash (used in) provided by financing activities				0	184
Effect of exchange rate changes on cash and equivalents				0	0
Net (decrease) increase in cash and equivalents				0	6
Cash and equivalents at beginning of period				0	0	0
Cash and equivalents at end of period				0	6	0
Reportable Legal Entities | WMG Acquisition Corp. | 3.625% Senior Secured Notes
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp					287
Reportable Legal Entities | WMG Acquisition Corp. | 4.125% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					(40)
Reportable Legal Entities | WMG Acquisition Corp. | 4.875% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					(30)
Reportable Legal Entities | WMG Acquisition Corp. | 5.625% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					(27)
Reportable Legal Entities | WMG Acquisition Corp. Consolidated
Cash flows from operating activities
Net income				122	86
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization				71	68
Unrealized gains and remeasurement of foreign-denominated loans				5	(13)
Deferred income taxes				(29)	11
Loss on extinguishment of debt					3
Net gain on divestitures and investments				1	(15)
Non-cash interest expense				1	2
Equity-based compensation expense				(7)	12
Equity gains, including distributions				0	0
Changes in operating assets and liabilities:
Accounts receivable, net				(101)	(88)
Inventories				10	13
Royalty advances				(38)	(28)
Accounts payable and accrued liabilities				(44)	(92)
Royalty payables				84	92
Accrued interest				(11)	(7)
Operating lease liabilities				1
Deferred revenue				(21)	(5)
Other balance sheet changes				34	53
Net cash provided by operating activities				78	92
Cash flows from investing activities
Acquisition of music publishing rights, net				(11)	(5)
Capital expenditures				(15)	(26)
Investments and acquisitions of businesses, net				(6)	(207)
Proceeds from the sale of investments					0
Advances from issuer				0	0
Net cash used in investing activities				(32)	(238)
Cash flows from financing activities
Dividend by Acquisition Corp. to Holdings Corp.				(206)
Call premiums paid and deposit on early redemption of debt					(2)
Deferred financing costs paid					(4)
Distribution to noncontrolling interest holder				(1)	(2)
Dividends paid					0
Change in due to (from) issuer				0	0
Net cash (used in) provided by financing activities				(207)	182
Effect of exchange rate changes on cash and equivalents				4	(2)
Net (decrease) increase in cash and equivalents				(157)	34
Cash and equivalents at beginning of period				619	514	514
Cash and equivalents at end of period				462	548	619
Reportable Legal Entities | WMG Acquisition Corp. Consolidated | 3.625% Senior Secured Notes
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp					287
Reportable Legal Entities | WMG Acquisition Corp. Consolidated | 4.125% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					(40)
Reportable Legal Entities | WMG Acquisition Corp. Consolidated | 4.875% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					(30)
Reportable Legal Entities | WMG Acquisition Corp. Consolidated | 5.625% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					(27)
Reportable Legal Entities | WMG Holdings Corp.
Cash flows from operating activities
Net income				120	86
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization				0	0
Unrealized gains and remeasurement of foreign-denominated loans				0	0
Deferred income taxes				0	0
Loss on extinguishment of debt					0
Net gain on divestitures and investments				0	0
Non-cash interest expense				0	0
Equity-based compensation expense				0	0
Equity gains, including distributions				(120)	(86)
Changes in operating assets and liabilities:
Accounts receivable, net				0	0
Inventories				0	0
Royalty advances				0	0
Accounts payable and accrued liabilities				0	0
Royalty payables				0	0
Accrued interest				0	0
Operating lease liabilities				0
Deferred revenue				0	0
Other balance sheet changes				0	0
Net cash provided by operating activities				0	0
Cash flows from investing activities
Acquisition of music publishing rights, net				0	0
Capital expenditures				0	0
Investments and acquisitions of businesses, net				0	0
Proceeds from the sale of investments					0
Advances from issuer				0	0
Net cash used in investing activities				0	0
Cash flows from financing activities
Dividend by Acquisition Corp. to Holdings Corp.				0
Call premiums paid and deposit on early redemption of debt					0
Deferred financing costs paid					0
Distribution to noncontrolling interest holder				0	0
Dividends paid					0
Change in due to (from) issuer				0	0
Net cash (used in) provided by financing activities				0	0
Effect of exchange rate changes on cash and equivalents				0	0
Net (decrease) increase in cash and equivalents				0	0
Cash and equivalents at beginning of period				0	0	0
Cash and equivalents at end of period				0	0	0
Reportable Legal Entities | WMG Holdings Corp. | 3.625% Senior Secured Notes
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp					0
Reportable Legal Entities | WMG Holdings Corp. | 4.125% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					0
Reportable Legal Entities | WMG Holdings Corp. | 4.875% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					0
Reportable Legal Entities | WMG Holdings Corp. | 5.625% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					0
Eliminations
Cash flows from operating activities
Net income				(240)	(172)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization				0	0
Unrealized gains and remeasurement of foreign-denominated loans				0	0
Deferred income taxes				0	0
Loss on extinguishment of debt					0
Net gain on divestitures and investments				0	0
Non-cash interest expense				0	0
Equity-based compensation expense				0	0
Equity gains, including distributions				240	172
Changes in operating assets and liabilities:
Accounts receivable, net				0	0
Inventories				0	0
Royalty advances				0	0
Accounts payable and accrued liabilities				0	0
Royalty payables				0	0
Accrued interest				0	0
Operating lease liabilities				0
Deferred revenue				0	0
Other balance sheet changes				0	0
Net cash provided by operating activities				0	0
Cash flows from investing activities
Acquisition of music publishing rights, net				0	0
Capital expenditures				0	0
Investments and acquisitions of businesses, net				0	0
Proceeds from the sale of investments					0
Advances from issuer				0	0
Net cash used in investing activities				0	0
Cash flows from financing activities
Dividend by Acquisition Corp. to Holdings Corp.				0
Call premiums paid and deposit on early redemption of debt					0
Deferred financing costs paid					0
Distribution to noncontrolling interest holder				0	0
Dividends paid					0
Change in due to (from) issuer				0	0
Net cash (used in) provided by financing activities				0	0
Effect of exchange rate changes on cash and equivalents				0	0
Net (decrease) increase in cash and equivalents				0	0
Cash and equivalents at beginning of period				0	0	0
Cash and equivalents at end of period				0	0	0
Eliminations | 3.625% Senior Secured Notes
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp					0
Eliminations | 4.125% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					0
Eliminations | 4.875% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					0
Eliminations | 5.625% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					0
Eliminations | WMG Acquisition Corp.
Cash flows from operating activities
Net income				(216)	(212)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization				0	0
Unrealized gains and remeasurement of foreign-denominated loans				0	1
Deferred income taxes				0	0
Loss on extinguishment of debt					0
Net gain on divestitures and investments				0	0
Non-cash interest expense				0	0
Equity-based compensation expense				0	0
Equity gains, including distributions				240	281
Changes in operating assets and liabilities:
Accounts receivable, net				0	0
Inventories				0	0
Royalty advances				0	0
Accounts payable and accrued liabilities				(24)	(70)
Royalty payables				0	0
Accrued interest				0	0
Operating lease liabilities				0
Deferred revenue				0	0
Other balance sheet changes				0	0
Net cash provided by operating activities				0	0
Cash flows from investing activities
Acquisition of music publishing rights, net				0	0
Capital expenditures				0	0
Investments and acquisitions of businesses, net				0	0
Proceeds from the sale of investments					0
Advances from issuer				(33)	84
Net cash used in investing activities				(33)	84
Cash flows from financing activities
Dividend by Acquisition Corp. to Holdings Corp.				0
Call premiums paid and deposit on early redemption of debt					0
Deferred financing costs paid					0
Distribution to noncontrolling interest holder				0	0
Dividends paid					0
Change in due to (from) issuer				33	(84)
Net cash (used in) provided by financing activities				33	(84)
Effect of exchange rate changes on cash and equivalents				0	0
Net (decrease) increase in cash and equivalents				0	0
Cash and equivalents at beginning of period				0	0	0
Cash and equivalents at end of period				$ 0	0	$ 0
Eliminations | WMG Acquisition Corp. | 3.625% Senior Secured Notes
Cash flows from financing activities
Proceeds from issuance of Acquisition Corp					0
Eliminations | WMG Acquisition Corp. | 4.125% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					0
Eliminations | WMG Acquisition Corp. | 4.875% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					0
Eliminations | WMG Acquisition Corp. | 5.625% Senior Secured Notes
Cash flows from financing activities
Repayment of Senior Secured Notes					$ 0