Summary of Significant Accounting Policies (Policies)	3 Months Ended
Dec. 31, 2021
Accounting Policies [Abstract]
Interim Financial Statements	Interim Financial Statements The accompanying unaudited consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all the information and notes required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three months ended December 31, 2021 are not necessarily indicative of the results that may be expected for the fiscal year ending September 30, 2022. The consolidated balance sheet at September 30, 2021 has been derived from the audited consolidated financial statements at that date but does not include all the information and notes required by U.S. GAAP for complete financial statements. For further information, refer to the consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the fiscal year ended September 30, 2021 (File No. 001-32502).
Basis of Consolidation	Basis of Consolidation The accompanying financial statements present the consolidated accounts of all entities in which the Company has a controlling voting interest and/or variable interest required to be consolidated in accordance with U.S. GAAP. All intercompany balances and transactions have been eliminated. Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 810, Consolidation (“ASC 810”) requires the Company first evaluate its investments to determine if any investments qualify as a variable interest entity (“VIE”). A VIE is consolidated if the Company is deemed to be the primary beneficiary of the VIE, which is the party involved with the VIE that has both (i) the power to control the most significant activities of the VIE and (ii) either the obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. If an entity is not deemed to be a VIE, the Company consolidates the entity if the Company has a controlling voting interest. The Company maintains a 52-53 week fiscal year ending on the last Friday in each reporting period. The fiscal year ended September 30, 2022 includes 53 weeks, and the fiscal year ended September 30, 2021 included 52 weeks. The additional week in fiscal year 2022 falls in the fiscal quarter ended December 31, 2021. Accordingly, the results of operations for the three months ended December 31, 2021 reflect 14 weeks compared to 13 weeks for the three months ended December 31, 2020. All references to December 31, 2021 and December 31, 2020 relate to the periods ended December 31, 2021 and December 25, 2020, respectively. For convenience purposes, the Company continues to date its first-quarter financial statements as of December 31. The fiscal year ended September 30, 2021 ended on September 24, 2021.
Common Stock	Common Stock On February 28, 2020, the Company amended its certificate of incorporation to increase its authorized capital stock to 2,100,000,000 shares, consisting of 1,000,000,000 shares of Class A Common Stock, 1,000,000,000 shares of Class B Common Stock, and 100,000,000 shares of preferred stock, par value $1.00 per share. In addition, the February 28, 2020 amendment to the Company’s certificate of incorporation also gave effect to the reclassification and 477,242.614671815-for-1 stock split of the Company’s existing common stock outstanding into 510,000,000 shares of Class B Common Stock. Upon completion of the IPO and the exercise in full of the underwriters’ option to purchase additional shares, 88,550,000 shares of Class A Common Stock, 421,450,000 shares of Class B Common Stock and no shares of preferred stock were outstanding. In connection with the IPO, the Company’s board of directors and stockholders approved the Warner Music Group Corp. 2020 Omnibus Incentive Plan, or the “Omnibus Incentive Plan.” The Omnibus Incentive Plan provides for the grant of incentive common stock, stock options, restricted stock, restricted stock units (“RSUs”), performance awards and stock appreciation rights to employees, consultants and directors. The aggregate number of shares of common stock available for issuance under the Omnibus Incentive Plan is 31,169,099 shares of Class A Common Stock over the 10-year period from the date of adoption, including up to 1,000,000 shares of our Class A Common Stock in connection with the IPO. Since the IPO, a total of 215,613 shares of Class A Common Stock have been issued under the Omnibus Incentive Plan, which includes 151,046 and 2,553 shares issued during the three months ended December 31, 2021, and 2020, respectively. During the three months ended December 31, 2021, an aggregate of 4,670,910 shares of Class B Common Stock were converted to Class A Common Stock. In connection with the Senior Management Free Cash Flow Plan (the “Plan”), a remaining Plan participant redeemed a portion of vested Class B equity units of the LLC holding company, WMG Management Holdings, LLC (“Management LLC”). These Class B equity units were redeemed in exchange for a total of 510,165 shares of Class B Common Stock, which shares of Class B Common Stock converted to shares of Class A Common Stock upon the exchange. Additionally, during the three months ended December 31, 2021, Access converted 4,160,745 shares of Class B Common Stock to the same number of shares of Class A Common Stock, which it subsequently sold through open market sales, which is reflected as an exchange of Class B Common Stock in the consolidated statements of equity for the three months ended December 31, 2021.
Earnings per Share	Earnings per Share The consolidated statements of operations present basic and diluted earnings per share (“EPS”). The Company utilizes the two-class method to report earnings per share. The two-class method is an earnings allocation formula that determines earnings per share for each class of common stock according to dividends declared and participation rights in undistributed earnings. Undistributed earnings allocated to participating securities are subtracted from net income in determining net income attributable to common stockholders.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock-based payments in accordance with ASC 718, Compensation—Stock Compensation (“ASC 718”). Stock-based compensation consists primarily of restricted stock units (“RSUs”) granted to eligible employees and executives under the Omnibus Incentive Plan. The Company measures compensation expense for RSUs based on the fair value of the award on the date of grant. The grant date fair value is based on the closing market price of the Company’s Class A Common Stock on the date of grant. The Company accounts for forfeitures as they occur. Stock-based compensation is recognized on a straight-line basis over the requisite service period, which is generally four years except for certain one-year awards issued in connection with the IPO. The Company also grants unvested restricted stock to the Company’s directors. The Company recognizes stock-based compensation expense equal to the grant date fair value of the restricted stock, based on the closing stock price on grant date, on a straight-line basis over the requisite service period of the awards, which is generally one year. The Company also recognizes stock-based compensation under the Plan. The awards outstanding under the Plan are equity-classified. The Company recognized approximately $24 million of non-cash stock-based compensation expense for the three months ended December 31, 2021, of which $22 million was recorded to additional paid-in capital, and a remaining $2 million has been classified as a share-based compensation liability as of December 31, 2021. The share-based compensation liability represents executive awards that have not yet been granted under the Omnibus Incentive Plan, where a total value is known and settlement will occur in a variable number of RSUs. During the three months ended December 31, 2021, $9 million was reclassified from share-based compensation liability to additional paid-in capital, representing the grant date fair value of RSUs granted which were previously classified as a share-based compensation liability as of September 30, 2021. The Company recognized approximately $6 million of non-cash stock-based compensation expense for the three months ended December 31, 2020.
Income Taxes	Income Taxes The Company uses the estimated annual effective tax rate method in computing its interim tax provision. Certain items, including those deemed to be unusual and infrequent are excluded from the estimated annual effective tax rate. In such cases, the actual tax expense or benefit is reported in the same period as the related item. Certain tax effects are also not reflected in the estimated annual effective tax rate, primarily certain changes in the realizability of deferred tax assets and uncertain tax positions.
New Accounting Pronouncements	New Accounting Pronouncements Recently Adopted Accounting Pronouncements In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes (“ASU 2019-12”). This ASU eliminates certain exceptions to the general principles in ASC 740, Income Taxes. Specifically, it eliminates the exception to (1) the incremental approach for intraperiod tax allocation when there is a loss from continuing operations, and income or a gain from other items; (2) the requirement to recognize a deferred tax liability for equity method investments when a foreign subsidiary becomes an equity method investment; (3) the ability not to recognize a deferred tax liability for a foreign subsidiary when a foreign equity method investment becomes a subsidiary; and (4) the general methodology for calculating income taxes in an interim period when a year-to-date loss exceeds the anticipated loss for the year. ASU 2019-12 also simplifies U.S. GAAP by making other changes. The Company adopted ASU 2019-12 in the first quarter of fiscal 2022 and this adoption did not have a material impact on the Company’s consolidated financial statements. In August 2020, the FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity's Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity (“ASU 2020-06”). ASU 2020-06 simplifies the accounting for convertible instruments by eliminating the cash conversion and beneficial conversion feature models used to separately account for embedded conversion features as a component of equity. Instead, the entity will account for the convertible debt or convertible preferred stock securities as a single unit of account, unless the conversion feature requires bifurcation and recognition as derivatives. Additionally, the guidance requires entities to use the if-converted method for all convertible instruments in the diluted earnings per share calculation and include the effect of potential share settlement for instruments that may be settled in cash or shares. The Company adopted ASU 2020-06 in the first quarter of fiscal year 2022 and this adoption did not have any impact on the Company’s consolidated financial statements.

Summary of Significant Accounting Policies (Policies)

3 Months Ended

Dec. 31, 2021

The accompanying unaudited consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all the information and notes required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three months ended December 31, 2021 are not necessarily indicative of the results that may be expected for the fiscal year ending September 30, 2022.

The consolidated balance sheet at September 30, 2021 has been derived from the audited consolidated financial statements at that date but does not include all the information and notes required by U.S. GAAP for complete financial statements.

For further information, refer to the consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the fiscal year ended September 30, 2021 (File No. 001-32502).

Basis of Consolidation

The accompanying financial statements present the consolidated accounts of all entities in which the Company has a controlling voting interest and/or variable interest required to be consolidated in accordance with U.S. GAAP. All intercompany balances and transactions have been eliminated.

Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 810, Consolidation (“ASC 810”) requires the Company first evaluate its investments to determine if any investments qualify as a variable interest entity (“VIE”). A VIE is consolidated if the Company is deemed to be the primary beneficiary of the VIE, which is the party involved with the VIE that has both (i) the power to control the most significant activities of the VIE and (ii) either the obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. If an entity is not deemed to be a VIE, the Company consolidates the entity if the Company has a controlling voting interest.

The Company maintains a 52-53 week fiscal year ending on the last Friday in each reporting period. The fiscal year ended September 30, 2022 includes 53 weeks, and the fiscal year ended September 30, 2021 included 52 weeks. The additional week in fiscal year 2022 falls in the fiscal quarter ended December 31, 2021. Accordingly, the results of operations for the three months ended December 31, 2021 reflect 14 weeks compared to 13 weeks for the three months ended December 31, 2020.

All references to December 31, 2021 and December 31, 2020 relate to the periods ended December 31, 2021 and December 25, 2020, respectively. For convenience purposes, the Company continues to date its first-quarter financial statements as of December 31. The fiscal year ended September 30, 2021 ended on September 24, 2021.

Common Stock

On February 28, 2020, the Company amended its certificate of incorporation to increase its authorized capital stock to 2,100,000,000 shares, consisting of 1,000,000,000 shares of Class A Common Stock, 1,000,000,000 shares of Class B Common Stock, and 100,000,000 shares of preferred stock, par value $1.00 per share. In addition, the February 28, 2020 amendment to the Company’s certificate of incorporation also gave effect to the reclassification and 477,242.614671815-for-1 stock split of the Company’s existing common stock outstanding into 510,000,000 shares of Class B Common Stock. Upon completion of the IPO and the exercise in full of the underwriters’ option to purchase additional shares, 88,550,000 shares of Class A Common Stock, 421,450,000 shares of Class B Common Stock and no shares of preferred stock were outstanding.

In connection with the IPO, the Company’s board of directors and stockholders approved the Warner Music Group Corp. 2020 Omnibus Incentive Plan, or the “Omnibus Incentive Plan.” The Omnibus Incentive Plan provides for the grant of incentive common stock, stock options, restricted stock, restricted stock units (“RSUs”), performance awards and stock appreciation rights to employees, consultants and directors. The aggregate number of shares of common stock available for issuance under the Omnibus Incentive Plan is 31,169,099 shares of Class A Common Stock over the 10-year period from the date of adoption, including up to 1,000,000 shares of our Class A Common Stock in connection with the IPO.

Since the IPO, a total of 215,613 shares of Class A Common Stock have been issued under the Omnibus Incentive Plan, which includes 151,046 and 2,553 shares issued during the three months ended December 31, 2021, and 2020, respectively.

During the three months ended December 31, 2021, an aggregate of 4,670,910 shares of Class B Common Stock were converted to Class A Common Stock. In connection with the Senior Management Free Cash Flow Plan (the “Plan”), a remaining Plan participant redeemed a portion of vested Class B equity units of the LLC holding company, WMG Management Holdings, LLC (“Management LLC”). These Class B equity units were redeemed in exchange for a total of 510,165 shares of Class B Common Stock, which shares of Class B Common Stock converted to shares of Class A Common Stock upon the exchange.

Additionally, during the three months ended December 31, 2021, Access converted 4,160,745 shares of Class B Common Stock to the same number of shares of Class A Common Stock, which it subsequently sold through open market sales, which is reflected as an exchange of Class B Common Stock in the consolidated statements of equity for the three months ended December 31, 2021.

Earnings per Share

The consolidated statements of operations present basic and diluted earnings per share (“EPS”). The Company utilizes the two-class method to report earnings per share. The two-class method is an earnings allocation formula that determines earnings per share for each class of common stock according to dividends declared and participation rights in undistributed earnings. Undistributed earnings allocated to participating securities are subtracted from net income in determining net income attributable to common stockholders.

Stock-Based Compensation

The Company accounts for stock-based payments in accordance with ASC 718, Compensation—Stock Compensation (“ASC 718”). Stock-based compensation consists primarily of restricted stock units (“RSUs”) granted to eligible employees and executives under the Omnibus Incentive Plan. The Company measures compensation expense for RSUs based on the fair value of the award on the date of grant. The grant date fair value is based on the closing market price of the Company’s Class A Common Stock on the date of grant. The Company accounts for forfeitures as they occur. Stock-based compensation is recognized on a straight-line basis over the requisite service period, which is generally four years except for certain one-year awards issued in connection with the IPO.

The Company also grants unvested restricted stock to the Company’s directors. The Company recognizes stock-based compensation expense equal to the grant date fair value of the restricted stock, based on the closing stock price on grant date, on a straight-line basis over the requisite service period of the awards, which is generally one year.

The Company also recognizes stock-based compensation under the Plan. The awards outstanding under the Plan are equity-classified.

The Company recognized approximately $24 million of non-cash stock-based compensation expense for the three months ended December 31, 2021, of which $22 million was recorded to additional paid-in capital, and a remaining $2 million has been classified as a share-based compensation liability as of December 31, 2021. The share-based compensation liability represents executive awards that have not yet been granted under the Omnibus Incentive Plan, where a total value is known and settlement will occur in a variable number of RSUs. During the three months ended December 31, 2021, $9 million was reclassified from share-based compensation liability to additional paid-in capital, representing the grant date fair value of RSUs granted which were previously classified as a share-based compensation liability as of September 30, 2021. The Company recognized approximately $6 million of non-cash stock-based compensation expense for the three months ended December 31, 2020.

Income Taxes

The Company uses the estimated annual effective tax rate method in computing its interim tax provision. Certain items, including those deemed to be unusual and infrequent are excluded from the estimated annual effective tax rate. In such cases, the actual tax expense or benefit is reported in the same period as the related item. Certain tax effects are also not reflected in the estimated annual effective tax rate, primarily certain changes in the realizability of deferred tax assets and uncertain tax positions.

New Accounting Pronouncements

Recently Adopted Accounting Pronouncements

In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes (“ASU 2019-12”). This ASU eliminates certain exceptions to the general principles in ASC 740, Income Taxes. Specifically, it eliminates the exception to (1) the incremental approach for intraperiod tax allocation when there is a loss from continuing operations, and income or a gain from other items; (2) the requirement to recognize a deferred tax liability for equity method investments when a foreign subsidiary becomes an equity method investment; (3) the ability not to recognize a deferred tax liability for a foreign subsidiary when a foreign equity method investment becomes a subsidiary; and (4) the general methodology for calculating income taxes in an interim period when a year-to-date loss exceeds the anticipated loss for the year. ASU 2019-12 also simplifies U.S. GAAP by making other changes. The Company adopted ASU 2019-12 in the first quarter of fiscal 2022 and this adoption did not have a material impact on the Company’s consolidated financial statements.

In August 2020, the FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity's Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity (“ASU 2020-06”). ASU 2020-06 simplifies the accounting for convertible instruments by eliminating the cash conversion and beneficial conversion feature models used to separately account for embedded conversion features as a component of equity. Instead, the entity will account for the convertible debt or convertible preferred stock securities as a single unit of account, unless the conversion feature requires bifurcation and recognition as derivatives. Additionally, the guidance requires entities to use the if-converted method for all convertible instruments in the diluted earnings per share calculation and include the effect of potential share settlement for instruments that may be settled in cash or shares. The Company adopted ASU 2020-06 in the first quarter of fiscal year 2022 and this adoption did not have any impact on the Company’s consolidated financial statements.