Decommissioning Trust Funds (Narrative) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Decommissioning Trust Funds [Abstract]
Deferred taxes on unrealized gains/(losses) recorded in OCI for non-regulated decommissioning trusts			$ 187		$ 149
Amortized cost of debt securities	1,609.0		1,609.0		1,530.0
Average coupon rate of debt securities	4.01%		4.01%
Average duration of debt securities, years	5.45		5.45
Average maturity of debt securities, years	8.67		8.67
Proceeds from the dispositions of debt securities	409.0	144.0	945.0	636.0
Gains from dispositions of debt securities, gross	11.00	4.00	23.00	8.00
Losses from dispositions of debt securities, gross	2.00	1.00	4.00	6.00
Entergy Arkansas [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	205.6		205.6		197.5
Average coupon rate of debt securities	3.35%		3.35%
Average duration of debt securities, years	5.11		5.11
Average maturity of debt securities, years	5.78		5.78
Proceeds from the dispositions of debt securities	33.7	15.1	88.4	46.2
Gains from dispositions of debt securities, gross	0.70	0.70	2.70	1.30
Losses from dispositions of debt securities, gross	0.04	0.03	0.04	0.03
Entergy Gulf States Louisiana [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	170.5		170.5		166.9
Average coupon rate of debt securities	4.77%		4.77%
Average duration of debt securities, years	5.71		5.71
Average maturity of debt securities, years	8.81		8.81
Proceeds from the dispositions of debt securities	22.7	8.8	60.8	20.7
Gains from dispositions of debt securities, gross	0.90	0.40	2.40	0.40
Losses from dispositions of debt securities, gross	0.03	0.03	0.03	0.07
Entergy Louisiana [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	101.0		101.0		91.9
Average coupon rate of debt securities	3.77%		3.77%
Average duration of debt securities, years	5.43		5.43
Average maturity of debt securities, years	9.50		9.50
Proceeds from the dispositions of debt securities	3.5	1.7	10.3	7.8
Gains from dispositions of debt securities, gross	0.01	0.03	0.04	0.09
Losses from dispositions of debt securities, gross	0.03	0.02	0.03	0.03
System Energy [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	190.9		190.9		175.1
Average coupon rate of debt securities	2.87%		2.87%
Average duration of debt securities, years	4.65		4.65
Average maturity of debt securities, years	6.59		6.59
Proceeds from the dispositions of debt securities	97.8	17.9	223.2	106.5
Gains from dispositions of debt securities, gross	1.80	0.10	3.00	0.50
Losses from dispositions of debt securities, gross	$ 0.10	$ 0.02	$ 0.20	$ 1.00