Decommissioning Trust Funds (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 counterparty	Dec. 31, 2013 counterparty	Dec. 31, 2012
Number of Hedge Contracts Counterparties	1	9
Decommissioning Trust Funds [Abstract]
Deferred taxes on unrealized gains/(losses) recorded in OCI for non-regulated decommissioning trusts	$ 396	$ 329
Amortized cost of debt securities	2,019.0	1,843.0
Average coupon rate of debt securities	3.31%
Proceeds from the dispositions of debt securities	1,872.0	2,032.0	2,074.0
Gains from dispositions of debt securities, gross	39.0	91.0	39.0
Losses from dispositions of debt securities, gross	8.00	11.00	7.00
Average Duration of Debt Securities in Years	5 years 7 months 25 days
Average Maturity of Debt Securities, Years	8 years 5 months 13 days
Hedge Contracts In Liability Position	1	187
Cash Collateral Requirement		47
Entergy Arkansas [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	277.4	248.9
Average coupon rate of debt securities	2.55%
Proceeds from the dispositions of debt securities	181.5	266.4	144.3
Gains from dispositions of debt securities, gross	8.7	16.8	3.4
Losses from dispositions of debt securities, gross	0.30	0.60	0.10
Average Duration of Debt Securities in Years	4 years 8 months 5 days
Average Maturity of Debt Securities, Years	5 years 3 months 27 days
Entergy Gulf States Louisiana [Member]
Percentage Interest in River Bend	30.00%
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	231.5	199.1
Average coupon rate of debt securities	4.40%
Proceeds from the dispositions of debt securities	173.5	193.8	131.0
Gains from dispositions of debt securities, gross	1.9	16.0	6.7
Losses from dispositions of debt securities, gross	0.30	0.10	0.04
Average Duration of Debt Securities in Years	5 years 10 months 14 days
Average Maturity of Debt Securities, Years	11 years 1 month 16 days
Entergy Louisiana [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	137.9	120.6
Average coupon rate of debt securities	3.05%
Proceeds from the dispositions of debt securities	43.2	109.9	27.6
Gains from dispositions of debt securities, gross	0.3	6.0	0.2
Losses from dispositions of debt securities, gross	0.02	0.10	0.04
Average Duration of Debt Securities in Years	5 years 4 months 22 days
Average Maturity of Debt Securities, Years	8 years 4 months 22 days
System Energy [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	251.0	223.4
Average coupon rate of debt securities	2.23%
Proceeds from the dispositions of debt securities	392.9	215.5	349.4
Gains from dispositions of debt securities, gross	1.8	1.5	3.6
Losses from dispositions of debt securities, gross	$ 0.90	$ 1.30	$ 0.30
Average Duration of Debt Securities in Years	4 years 5 months 24 days
Average Maturity of Debt Securities, Years	5 years 11 months 13 days