Asset Retirement Obligations (Cumulative Decommissioning And Retirement Cost Liabilities And Expenses) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation		$ 6,185.8	$ 6,706.8	$ 4,790.2
Accretion		431.5	359.9
Change in Cash Flow Estimate		(104.6)	534.5
Spending	$ (727.3)	(120.6)	(140.3)
Asset Retirement Obligation, Liabilities Incurred			1,162.5
Entergy Arkansas [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation		981.2	924.4	872.3
Accretion		56.8	53.6
Change in Cash Flow Estimate		0.0	0.0
Spending		0.0	(1.5)
Asset Retirement Obligation, Liabilities Incurred			0.0
Entergy Louisiana [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation		1,140.5	1,082.7	1,027.9
Accretion		57.8	54.8
Change in Cash Flow Estimate		0.0	0.0
Spending		0.0	0.0
Asset Retirement Obligation, Liabilities Incurred			0.0
Entergy Mississippi [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation		9.2	8.7	8.3
Accretion		0.5	0.4
Change in Cash Flow Estimate		0.0	0.0
Spending		0.0	0.0
Asset Retirement Obligation, Liabilities Incurred			0.0
Entergy New Orleans [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation		3.1	2.9	2.7
Accretion		0.2	0.2
Change in Cash Flow Estimate		0.0	0.0
Spending		0.0	0.0
Asset Retirement Obligation, Liabilities Incurred			0.0
Entergy Texas [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation		6.8	6.5	6.1
Accretion		0.3	0.4
Change in Cash Flow Estimate		0.0	0.0
Spending		0.0	0.0
Asset Retirement Obligation, Liabilities Incurred			0.0
System Energy [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation		861.7	854.2	803.4
Accretion		43.4	50.8
Change in Cash Flow Estimate		(35.9)	0.0
Spending		0.0	0.0
Asset Retirement Obligation, Liabilities Incurred			0.0
Entergy Wholesale Commodities [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation		3,183.3	3,827.4	2,069.5
Accretion		272.5	199.7
Change in Cash Flow Estimate		(68.7)	534.5
Spending	(727.3)	(120.6)	(138.8)
Asset Retirement Obligation, Liabilities Incurred			1,162.5
Big Rock Point [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation		38.9	37.9	28.0
Accretion		3.1	2.2
Change in Cash Flow Estimate		0.0	10.1
Spending		(2.1)	(2.4)
Asset Retirement Obligation, Liabilities Incurred			0.0
FitzPatrick [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation		0.0	714.3	0.0
Accretion		13.9	18.1
Change in Cash Flow Estimate		0.0	0.0
Spending	$ (727.3)	(0.9)	0.0
Asset Retirement Obligation, Liabilities Incurred			696.2
Indian Point 1 [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation		217.6	207.6	197.9
Accretion		17.7	17.1
Change in Cash Flow Estimate		0.0	(0.3)
Spending		(7.7)	(7.1)
Asset Retirement Obligation, Liabilities Incurred			0.0
Indian Point 2 [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation		708.7	653.1	390.1
Accretion		55.8	33.0
Change in Cash Flow Estimate		0.0	230.0
Spending		(0.2)	0.0
Asset Retirement Obligation, Liabilities Incurred			0.0
Indian Point 3 [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation		694.5	641.1	0.0
Accretion		53.5	12.1
Change in Cash Flow Estimate		0.0	162.7
Spending		(0.1)	0.0
Asset Retirement Obligation, Liabilities Incurred			466.3
Palisades [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation		470.4	500.3	342.0
Accretion		41.3	29.5
Change in Cash Flow Estimate		(68.7)	128.8
Spending		(2.5)	0.0
Asset Retirement Obligation, Liabilities Incurred			0.0
Pilgrim [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation		651.4	602.3	551.2
Accretion		52.8	48.4
Change in Cash Flow Estimate		0.0	3.2
Spending		(3.7)	(0.5)
Asset Retirement Obligation, Liabilities Incurred			0.0
Vermont Yankee [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation		401.5	470.5	560.0
Accretion		34.4	39.3
Change in Cash Flow Estimate		0.0	0.0
Spending		(103.4)	(128.8)
Asset Retirement Obligation, Liabilities Incurred			0.0
Utility [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation		3,002.5	2,879.4	2,720.7
Accretion		159.0	160.2
Change in Cash Flow Estimate		(35.9)	0.0
Spending		0.0	(1.5)
Asset Retirement Obligation, Liabilities Incurred			0.0
Other Affiliates [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation		0.3	0.3	$ 0.3
Accretion		0.0	0.0
Change in Cash Flow Estimate		0.0	0.0
Spending		$ 0.0	0.0
Asset Retirement Obligation, Liabilities Incurred			$ 0.0