Decommissioning Trust Funds (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Mar. 31, 2013
Decommissioning Trust Funds [Abstract]
Deferred taxes on unrealized gains/(losses) recorded in OCI for non-regulated decommissioning trusts			$ 256		$ 211
Amortized cost of debt securities	1,701.0		1,701.0		1,637.0
Average coupon rate of debt securities	3.62%		3.62%
Average duration of debt securities, years						5 years 2 months 8 days
Average maturity of debt securities, years						7 years 11 months 29 days
Proceeds from the dispositions of debt securities	382.00	409.00	780.00	945.00
Gains from dispositions of debt securities, gross	16.00	11.00	22.00	23.00
Losses from dispositions of debt securities, gross	1.00	2.00	3.00	4.00
Entergy Arkansas [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	233.4		233.4		202.3
Average coupon rate of debt securities	2.82%		2.82%
Average duration of debt securities, years						5 years 3 months 3 days
Average maturity of debt securities, years						6 years 0 months 3 days
Proceeds from the dispositions of debt securities	87.00	33.70	143.10	88.40
Gains from dispositions of debt securities, gross	7.30	0.70	8.70	2.70
Losses from dispositions of debt securities, gross	0.01	0.04	0.10	0.04
Entergy Gulf States Louisiana [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	179.9		179.9		174.1
Average coupon rate of debt securities	4.61%		4.61%
Average duration of debt securities, years						5 years 5 months 15 days
Average maturity of debt securities, years						8 years 2 months 5 days
Proceeds from the dispositions of debt securities	23.40	22.70	46.70	60.80
Gains from dispositions of debt securities, gross	5.20	0.90	6.30	2.40
Losses from dispositions of debt securities, gross	0.01	0.03	0.01	0.03
Entergy Louisiana [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	107.3		107.3		102.6
Average coupon rate of debt securities	3.53%		3.53%
Average duration of debt securities, years						5 years 0 months 26 days
Average maturity of debt securities, years						9 years 0 months 0 days
Proceeds from the dispositions of debt securities	5.90	3.50	9.50	10.30
Gains from dispositions of debt securities, gross	0.01	0.01	0.05	0.04
Losses from dispositions of debt securities, gross	0.01	0.03	0.02	0.03
System Energy [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	210.5		210.5		197.8
Average coupon rate of debt securities	2.54%		2.54%
Average duration of debt securities, years						4 years 5 months 1 day
Average maturity of debt securities, years						5 years 11 months 26 days
Proceeds from the dispositions of debt securities	65.60	97.80	91.20	223.20
Gains from dispositions of debt securities, gross	0.80	1.80	0.80	3.00
Losses from dispositions of debt securities, gross	$ 0.30	$ 0.10	$ 0.40	$ 0.20