Schedule of Stock by Class, Equity [Roll Forward]

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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- Definition

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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- Definition

Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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- Definition

Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

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- Definition

Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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- Definition

Number of new stock issued during the period.

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- Definition

Number, after forfeiture, of shares or units issued under share-based payment arrangement. Excludes shares or units issued under employee stock ownership plan (ESOP).

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Number of previously issued common shares repurchased by the issuing entity and held in treasury.

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Changes in Capital Structure - Changes in NRG's Common Stock Issued and Outstanding (Details) - shares		3 Months Ended
	Mar. 09, 2023	Mar. 31, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Common stock, shares authorized (in shares)		500,000,000	500,000,000
Schedule of Stock by Class, Equity [Roll Forward]
Common, Balance as of beginning of period (in shares)		423,897,001
Treasury, Balance as of end of period (in shares)		(194,335,971)
Common, Outstanding, as of beginning of period (in shares)		229,561,030
Preferred, Balance as of end of period (in shares)		650,000
Common, Balance as of end of period (in shares)		424,292,409
Treasury, Balance as of end of period (in shares)		(194,335,971)
Preferred, Outstanding as of end of period (in shares)		650,000
Common, Outstanding, as of end of period (in shares)		229,956,438
Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)		395,408
Preferred Stock \| Series A Preferred Stock
Schedule of Stock by Class, Equity [Roll Forward]
Issuance of Series A Preferred Stock (in shares)	650,000	650,000
Common Stock
Schedule of Stock by Class, Equity [Roll Forward]
Common, Balance as of beginning of period (in shares)		423,897,001
Common, Balance as of end of period (in shares)		424,292,409
Common Stock \| Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)		395,408
Treasury Stock
Schedule of Stock by Class, Equity [Roll Forward]
Treasury, Balance as of end of period (in shares)		(194,335,971)
Treasury, Balance as of end of period (in shares)		(194,335,971)
Treasury Stock \| Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)		0