Schedule of Stock by Class, Equity [Roll Forward]

No definition available.

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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

Number of shares issued during the period as a result of an employee stock purchase plan.

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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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- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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- Definition

Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

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Changes in Capital Structure - Changes in NRG's common stock issued and outstanding (Details) - shares	1 Months Ended	3 Months Ended
	Apr. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
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]
Balance as of beginning of period (in shares)	423,839,804	423,547,174
Treasury shares, balance as of beginning of period (in shares)	(184,623,664)	(179,793,275)
Outstanding, as of beginning of period (in shares)	239,216,140	243,753,899
Shares repurchased (in shares)		(4,830,389)
Balance as of end of period (in shares)		423,839,804
Treasury shares, balance as of end of the period (in shares)		(184,623,664)
Outstanding, as of end of period (in shares)		239,216,140
Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)		292,630
Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Shares repurchased (in shares)	(2,014,734)
Outstanding, as of end of period (in shares)	237,283,560
Subsequent Event \| Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)	13,213
Subsequent Event \| Shares issued under ESPP
Schedule of Stock by Class, Equity [Roll Forward]
Stock issued under ESPP (in shares)	68,941
Common Stock
Schedule of Stock by Class, Equity [Roll Forward]
Balance as of beginning of period (in shares)	423,839,804	423,547,174
Shares repurchased (in shares)		0
Balance as of end of period (in shares)		423,839,804
Common Stock \| Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)		292,630
Common Stock \| Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Shares repurchased (in shares)	0
Balance as of end of period (in shares)	423,853,017
Common Stock \| Subsequent Event \| Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)	13,213
Common Stock \| Subsequent Event \| Shares issued under ESPP
Schedule of Stock by Class, Equity [Roll Forward]
Stock issued under ESPP (in shares)	0
Treasury
Schedule of Stock by Class, Equity [Roll Forward]
Treasury shares, balance as of beginning of period (in shares)	(184,623,664)	(179,793,275)
Shares repurchased (in shares)		(4,830,389)
Treasury shares, balance as of end of the period (in shares)		(184,623,664)
Treasury \| Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)		0
Treasury \| Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Shares repurchased (in shares)	(2,014,734)
Treasury shares, balance as of end of the period (in shares)	(186,569,457)
Treasury \| Subsequent Event \| Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)	0
Treasury \| Subsequent Event \| Shares issued under ESPP
Schedule of Stock by Class, Equity [Roll Forward]
Stock issued under ESPP (in shares)	68,941