Schedule of Stock by Class, Equity [Roll Forward]

No definition available.

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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	4 Months Ended
	May 07, 2020	Apr. 30, 2020	Mar. 31, 2020	May 07, 2020
Schedule of Stock by Class, Equity [Roll Forward]
Balance as of beginning of period (in shares)	422,979,893	422,979,893	421,890,790	421,890,790
Treasury shares, balance as of beginning of period (in shares)	(177,356,039)	(177,356,039)	(172,894,601)	(172,894,601)
Outstanding, as of beginning of period (in shares)	245,623,854	245,623,854	248,996,189	248,996,189
Shares issued under LTIPs (in shares)			1,089,103
Shares repurchased (in shares)			(4,461,438)
Balance as of end of period (in shares)			422,979,893
Treasury shares, balance as of end of the period (in shares)			(177,356,039)
Outstanding, as of end of period (in shares)			245,623,854
Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)	1,096
Stock issued under ESPP (in shares)		63,455
Shares repurchased (in shares)	(1,601,345)
Outstanding, as of end of period (in shares)	244,087,060			244,087,060
Common Stock
Schedule of Stock by Class, Equity [Roll Forward]
Balance as of beginning of period (in shares)	422,979,893	422,979,893	421,890,790	421,890,790
Shares issued under LTIPs (in shares)			1,089,103
Shares repurchased (in shares)			0
Balance as of end of period (in shares)			422,979,893
Common Stock \| Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)	1,096
Shares repurchased (in shares)	0
Balance as of end of period (in shares)	422,980,989			422,980,989
Treasury
Schedule of Stock by Class, Equity [Roll Forward]
Treasury shares, balance as of beginning of period (in shares)	(177,356,039)	(177,356,039)	(172,894,601)	(172,894,601)
Shares issued under LTIPs (in shares)			0
Shares repurchased (in shares)			(4,461,438)
Treasury shares, balance as of end of the period (in shares)			(177,356,039)
Treasury \| Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)	0
Shares repurchased (in shares)	(1,601,345)
Treasury shares, balance as of end of the period (in shares)	(178,893,929)			(178,893,929)
Capital Allocation Plan
Schedule of Stock by Class, Equity [Roll Forward]
Shares repurchased (in shares)			(5,171,501)
Capital Allocation Plan \| Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Shares repurchased (in shares)	(1,601,345)			(6,772,846)
ESPP \| Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Stock issued under ESPP (in shares)	63,455
ESPP \| Common Stock \| Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Stock issued under ESPP (in shares)	0
ESPP \| Treasury \| Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Stock issued under ESPP (in shares)	63,455