Decommissioning Trust Funds (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Mar. 31, 2017	Jan. 31, 2017
Decommissioning Trust Funds [Abstract]
Deferred taxes on unrealized gains/(losses) recorded in OCI for non-regulated decommissioning trusts			$ 472,000,000		$ 399,000,000
Amortized cost of debt securities	$ 2,398,000,000		$ 2,398,000,000		2,212,000,000
Average coupon rate of debt securities	3.21%		3.21%
Average duration of debt securities, years			6 years 2 months 3 days
Average maturity of debt securities, years			10 years 26 days
Proceeds from the dispositions of debt securities	$ 440,000,000	$ 564,000,000	$ 1,903,000,000	$ 1,797,000,000
Gains from dispositions of debt securities, gross	9,000,000	6,000,000	79,000,000	26,000,000
Losses from dispositions of debt securities, gross	2,000,000	1,000,000	9,000,000	6,000,000
Entergy Arkansas [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	$ 333,300,000		$ 333,300,000		310,100,000
Average coupon rate of debt securities	2.53%		2.53%
Average duration of debt securities, years			5 years 9 months 30 days
Average maturity of debt securities, years			6 years 9 months 12 days
Proceeds from the dispositions of debt securities	$ 51,900,000	61,200,000	$ 219,200,000	165,000,000
Gains from dispositions of debt securities, gross	40,000	400,000	11,700,000	1,600,000
Losses from dispositions of debt securities, gross	500	40,000	$ 200,000	300,000
Entergy Louisiana [Member]
Decommissioning Trust Funds [Abstract]
Percentage Interest in River Bend			30.00%
Amortized cost of debt securities	$ 470,700,000		$ 470,700,000		421,900,000
Average coupon rate of debt securities	3.84%		3.84%
Average duration of debt securities, years			5 years 9 months 4 days
Average maturity of debt securities, years			11 years 7 months 7 days
Proceeds from the dispositions of debt securities	$ 50,500,000	54,700,000	$ 176,100,000	178,200,000
Gains from dispositions of debt securities, gross	2,900,000	400,000	7,900,000	3,000,000
Losses from dispositions of debt securities, gross	100,000	100,000	400,000	200,000
System Energy [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	$ 327,800,000		$ 327,800,000		$ 309,100,000
Average coupon rate of debt securities	2.44%		2.44%
Average duration of debt securities, years			6 years 4 months 15 days
Average maturity of debt securities, years			8 years 10 months 17 days
Proceeds from the dispositions of debt securities	$ 54,600,000	103,500,000	$ 308,100,000	392,900,000
Gains from dispositions of debt securities, gross	200,000	700,000	700,000	3,200,000
Losses from dispositions of debt securities, gross	200,000	$ 100,000	1,500,000	$ 400,000
Fitzpatrick [Member]
Decommissioning Trust Funds [Abstract]
Decommissioning Fund Investments, Fair Value						$ 805,000,000	$ 793,000,000
Indian Point 3 [Member]
Decommissioning Trust Funds [Abstract]
Decommissioning Fund Investments, Fair Value	774,000,000		774,000,000				$ 726,000,000
Indian Point 1 [Member]
Decommissioning Trust Funds [Abstract]
Decommissioning Fund Investments, Fair Value	478,000,000		478,000,000
Indian Point 2 [Member]
Decommissioning Trust Funds [Abstract]
Decommissioning Fund Investments, Fair Value	607,000,000		607,000,000
Palisades [Member]
Decommissioning Trust Funds [Abstract]
Decommissioning Fund Investments, Fair Value	445,000,000		445,000,000
Pilgrim [Member]
Decommissioning Trust Funds [Abstract]
Decommissioning Fund Investments, Fair Value	1,037,000,000		1,037,000,000
Vermont Yankee [Member]
Decommissioning Trust Funds [Abstract]
Decommissioning Fund Investments, Fair Value	$ 601,000,000		$ 601,000,000