Decommissioning Trust Funds (Fair Value Of Debt Securities By Contractual Maturities) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair value of debt securities by contractual maturities
Less than 1 year	$ 70.0	$ 94.0
1 year - 5 years	801.0	783.0
5 years - 10 years	692.0	681.0
10 years - 15 years	176.0	173.0
15 years - 20 years	71.0	79.0
20 years+	316.0	275.0
Total	2,126.0	2,085.0
Entergy Arkansas [Member]
Fair value of debt securities by contractual maturities
Less than 1 year	16.7	14.9
1 year - 5 years	128.0	127.3
5 years - 10 years	136.0	128.2
10 years - 15 years	3.1	1.7
15 years - 20 years	1.0	1.0
20 years+	11.8	9.5
Total	296.6	282.6
Entergy Gulf States Louisiana [Member]
Fair value of debt securities by contractual maturities
Less than 1 year	7.2	6.4
1 year - 5 years	62.1	59.8
5 years - 10 years	63.1	68.3
10 years - 15 years	43.2	43.6
15 years - 20 years	14.0	14.8
20 years+	51.8	48.9
Total	241.4	241.8
Entergy Louisiana [Member]
Fair value of debt securities by contractual maturities
Less than 1 year	4.3	5.6
1 year - 5 years	60.2	58.2
5 years - 10 years	45.1	44.2
10 years - 15 years	7.5	7.3
15 years - 20 years	10.0	9.4
20 years+	19.4	19.3
Total	146.5	144.0
System Energy [Member]
Fair value of debt securities by contractual maturities
Less than 1 year	12.9	33.5
1 year - 5 years	163.8	139.7
5 years - 10 years	54.5	53.5
10 years - 15 years	3.8	3.4
15 years - 20 years	1.7	3.2
20 years+	27.6	22.0
Total	$ 264.3	$ 255.3