Decommissioning Trust Funds (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Decommissioning Trust Funds [Abstract]
Deferred taxes on unrealized gains/(losses) recorded in OCI for non-regulated decommissioning trusts	$ 329	$ 211
Amortized cost of debt securities	1,843.0	1,637.0
Average coupon rate of debt securities	3.43%
Average duration of debt securities, years	4 years 11 months 23 days
Average maturity of debt securities, years	7 years 6 months 4 days
Proceeds from the dispositions of debt securities	2,032.0	2,074.0	1,360.0
Gains from dispositions of debt securities, gross	91.0	39.0	29.0
Losses from dispositions of debt securities, gross	11.00	7.00	11.00
Entergy Arkansas [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	248.9	202.3
Average coupon rate of debt securities	2.73%
Average duration of debt securities, years	4 years 9 months 26 days
Average maturity of debt securities, years	5 years 6 months 7 days
Proceeds from the dispositions of debt securities	266.4	144.3	125.4
Gains from dispositions of debt securities, gross	16.8	3.4	3.9
Losses from dispositions of debt securities, gross	0.60	0.10	0.20
Entergy Gulf States Louisiana [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	199.1	174.1
Average coupon rate of debt securities	4.03%
Average duration of debt securities, years	5 years 1 month 17 days
Average maturity of debt securities, years	7 years 3 months 22 days
Proceeds from the dispositions of debt securities	193.8	131.0	76.8
Gains from dispositions of debt securities, gross	16.0	6.7	2.8
Losses from dispositions of debt securities, gross	0.10	0.04	0.50
Entergy Louisiana [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	120.6	102.6
Average coupon rate of debt securities	2.99%
Average duration of debt securities, years	4 years 5 months 23 days
Average maturity of debt securities, years	7 years 5 months 23 days
Proceeds from the dispositions of debt securities	109.9	27.6	19.9
Gains from dispositions of debt securities, gross	6.0	0.2	0.3
Losses from dispositions of debt securities, gross	0.10	0.04	0.20
System Energy [Member]
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	223.4	197.8
Average coupon rate of debt securities	2.44%
Average duration of debt securities, years	4 years 5 months 1 day
Average maturity of debt securities, years	6 years 0 months 7 days
Proceeds from the dispositions of debt securities	215.5	349.4	203.4
Gains from dispositions of debt securities, gross	1.5	3.6	2.7
Losses from dispositions of debt securities, gross	$ 1.30	$ 0.30	$ 1.20