Decommissioning Trust Funds (Fair Value Of Debt Securities By Contractual Maturities) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Fair value of debt securities by contractual maturities
Less than 1 year	$ 64.0	$ 94.0
1 year - 5 years	792.0	783.0
5 years - 10 years	693.0	681.0
10 years - 15 years	174.0	173.0
15 years - 20 years	68.0	79.0
20 years+	324.0	275.0
Total	2,115.0	2,085.0
Entergy Arkansas [Member]
Fair value of debt securities by contractual maturities
Less than 1 year	6.0	14.9
1 year - 5 years	138.4	127.3
5 years - 10 years	135.9	128.2
10 years - 15 years	2.5	1.7
15 years - 20 years	1.0	1.0
20 years+	17.8	9.5
Total	301.6	282.6
Entergy Gulf States Louisiana [Member]
Fair value of debt securities by contractual maturities
Less than 1 year	4.1	6.4
1 year - 5 years	71.4	59.8
5 years - 10 years	60.6	68.3
10 years - 15 years	42.0	43.6
15 years - 20 years	12.0	14.8
20 years+	51.2	48.9
Total	241.3	241.8
Entergy Louisiana [Member]
Fair value of debt securities by contractual maturities
Less than 1 year	9.8	5.6
1 year - 5 years	54.9	58.2
5 years - 10 years	44.4	44.2
10 years - 15 years	9.8	7.3
15 years - 20 years	9.4	9.4
20 years+	18.4	19.3
Total	146.7	144.0
System Energy [Member]
Fair value of debt securities by contractual maturities
Less than 1 year	16.5	33.5
1 year - 5 years	150.6	139.7
5 years - 10 years	69.3	53.5
10 years - 15 years	3.3	3.4
15 years - 20 years	1.6	3.2
20 years+	22.2	22.0
Total	$ 263.5	$ 255.3