The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6392676&loc=d3e7480-110848

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Amount of asset retirement obligations settled, or otherwise disposed of, during the period. This may include asset retirement obligations transferred to third parties associated with the sale of a long-lived asset.

+ References

+ Details

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Amount of increase (decrease) in the asset retirement obligation from changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 35
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6392603&loc=d3e7123-110846

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)(4)
-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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Asset Retirement Obligations (Cumulative Decommissioning And Retirement Cost Liabilities And Expenses) (Details) - USD ($) $ in Millions	1 Months Ended			8 Months Ended	12 Months Ended
	Dec. 31, 2019	Aug. 31, 2019	Jan. 31, 2019	Aug. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	$ 6,159.2				$ 6,469.5	$ 6,159.2	$ 6,923.4
Accretion					394.6	414.0
Change in Cash Flow Estimate						273.7
Spending				$ (1,406.3)	(84.3)	(45.6)
Entergy Arkansas [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	1,242.6				1,314.2	1,242.6	1,048.4
Accretion					73.3	68.0
Change in Cash Flow Estimate						126.2
Spending					(1.7)	0.0
Entergy Louisiana [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	1,497.3				1,573.3	1,497.3	1,280.3
Accretion					76.0	69.5
Change in Cash Flow Estimate						147.5
Spending					0.0	0.0
Entergy Mississippi [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	9.7				9.8	9.7	9.2
Accretion					0.6	0.5
Change in Cash Flow Estimate						0.0
Spending					(0.5)	0.0
Entergy New Orleans [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	3.5				3.8	3.5	3.3
Accretion					0.3	0.2
Change in Cash Flow Estimate						0.0
Spending					0.0	0.0
Entergy Texas [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	7.6				8.1	7.6	7.2
Accretion					0.5	0.4
Change in Cash Flow Estimate						0.0
Spending					0.0	0.0
System Energy [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	931.7				968.9	931.7	896.0
Accretion					37.2	35.7
Change in Cash Flow Estimate						0.0
Spending					0.0	0.0
Entergy Wholesale Commodities [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	0.5				0.5	0.5	0.4
Accretion					0.0	0.1
Change in Cash Flow Estimate						0.0
Spending					0.0	0.0
Big Rock Point [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	40.3				41.1	40.3	39.7
Accretion					3.3	3.2
Change in Cash Flow Estimate						0.0
Spending	0.0				(2.5)	(2.6)
Indian Point 1 [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	238.6				246.6	238.6	227.9
Accretion					20.4	19.5
Change in Cash Flow Estimate						0.0
Spending	0.0				(12.4)	(8.8)
Indian Point 2 [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	829.0				839.8	829.0	768.0
Accretion					69.4	65.5
Change in Cash Flow Estimate						0.0
Spending	0.0				(58.6)	(4.5)
Indian Point 3 [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	808.4				869.4	808.4	750.6
Accretion					67.4	62.5
Change in Cash Flow Estimate						0.0
Spending	0.0				(6.4)	(4.7)
Palisades [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	549.8				594.1	549.8	508.0
Accretion					46.4	42.9
Change in Cash Flow Estimate						0.0
Spending	0.0				$ (2.1)	(1.1)
Pilgrim [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	0.0					0.0	816.5
Accretion						44.1
Change in Cash Flow Estimate						0.0
Spending		$ (836.7)				(23.9)
Vermont Yankee [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	$ 0.0					0.0	$ 567.9
Accretion						1.7
Change in Cash Flow Estimate						0.0
Spending			$ (569.6)			$ 0.0