Decommissioning Trust Funds (Narrative) (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Decommissioning Trust Funds [Abstract]
Deferred taxes on unrealized gains/(losses) recorded in OCI for non-regulated decommissioning trusts	$ 400,000,000		$ 396,000,000
Amortized cost of debt securities	2,054,000,000		2,019,000,000
Average coupon rate of debt securities	3.33%
Average duration of debt securities, years	5 years 8 months 13 days
Average maturity of debt securities, years	8 years 9 months 1 day
Proceeds from the dispositions of debt securities	493,000,000	537,000,000
Gains from dispositions of debt securities, gross	26,000,000	6,000,000
Losses from dispositions of debt securities, gross	2,000,000	2,000,000
Entergy Arkansas [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	290,000,000		277,400,000
Average coupon rate of debt securities	2.43%
Average duration of debt securities, years	4 years 10 months 25 days
Average maturity of debt securities, years	5 years 7 months 22 days
Proceeds from the dispositions of debt securities	81,900,000	45,300,000
Gains from dispositions of debt securities, gross	5,100,000	100,000
Losses from dispositions of debt securities, gross	1,300	200,000
Entergy Gulf States Louisiana [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	232,800,000		231,500,000
Average coupon rate of debt securities	4.40%
Average duration of debt securities, years	5 years 8 months 20 days
Average maturity of debt securities, years	11 years 1 month 5 days
Proceeds from the dispositions of debt securities	21,700,000	30,300,000
Gains from dispositions of debt securities, gross	1,300,000	200,000
Losses from dispositions of debt securities, gross	700	200,000
Entergy Louisiana [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	138,500,000		137,900,000
Average coupon rate of debt securities	2.96%
Average duration of debt securities, years	5 years 3 months 23 days
Average maturity of debt securities, years	8 years 2 months 17 days
Proceeds from the dispositions of debt securities	3,900,000	18,100,000
Gains from dispositions of debt securities, gross	16,800	200,000
Losses from dispositions of debt securities, gross	4,900	3,900
System Energy [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	256,600,000		251,000,000
Average coupon rate of debt securities	2.25%
Average duration of debt securities, years	4 years 6 months 16 days
Average maturity of debt securities, years	6 years 1 month 13 days
Proceeds from the dispositions of debt securities	78,400,000	130,300,000
Gains from dispositions of debt securities, gross	400,000	1,000,000
Losses from dispositions of debt securities, gross	$ 100,000	$ 300,000