Decommissioning Trust Funds (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Decommissioning Trust Funds [Abstract]
Deferred taxes on unrealized gains/(losses) recorded in OCI for non-regulated decommissioning trusts			$ 318,000,000		$ 396,000,000
Amortized cost of debt securities	$ 2,123,000,000		$ 2,123,000,000		2,019,000,000
Average coupon rate of debt securities	3.30%		3.30%
Average duration of debt securities, years			5 years 8 months 12 days
Average maturity of debt securities, years			8 years 8 months 1 day
Proceeds from the dispositions of debt securities	$ 539,000,000	$ 465,000,000	$ 1,488,000,000	$ 1,447,000,000
Gains from dispositions of debt securities, gross	13,000,000	11,000,000	58,000,000	23,000,000
Losses from dispositions of debt securities, gross	4,000,000	2,000,000	7,000,000	5,000,000
Entergy Arkansas [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	$ 297,800,000		$ 297,800,000		277,400,000
Average coupon rate of debt securities	2.42%		2.42%
Average duration of debt securities, years			5 years 3 months 4 days
Average maturity of debt securities, years			6 years 26 days
Proceeds from the dispositions of debt securities	$ 44,000,000	85,100,000	$ 190,800,000	155,400,000
Gains from dispositions of debt securities, gross	400,000	8,100,000	5,800,000	8,500,000
Losses from dispositions of debt securities, gross	100,000	13,000	100,000	300,000
Entergy Louisiana [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	$ 146,000,000		$ 146,000,000		137,900,000
Average coupon rate of debt securities	2.93%		2.93%
Average duration of debt securities, years			5 years 18 days
Average maturity of debt securities, years			8 years 1 month 10 days
Proceeds from the dispositions of debt securities	$ 6,500,000	6,200,000	$ 18,300,000	35,900,000
Gains from dispositions of debt securities, gross	100,000	30,000	200,000	200,000
Losses from dispositions of debt securities, gross	42,100	3,700	53,700	7,800
System Energy [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	$ 273,100,000		$ 273,100,000		$ 251,000,000
Average coupon rate of debt securities	2.16%		2.16%
Average duration of debt securities, years			4 years 8 months 23 days
Average maturity of debt securities, years			6 years 3 months 26 days
Proceeds from the dispositions of debt securities	$ 163,400,000	101,400,000	$ 325,400,000	333,000,000
Gains from dispositions of debt securities, gross	2,400,000	200,000	3,200,000	1,600,000
Losses from dispositions of debt securities, gross	$ 200,000	$ 200,000	$ 300,000	$ 500,000