Decommissioning Trust Funds (Fair Value Of Debt Securities By Contractual Maturities) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Fair value of debt securities by contractual maturities
Less than 1 year	$ 226.0	$ 199.0
1 year - 5 years	1,342.0	1,066.0
5 years - 10 years	654.0	544.0
10 years - 15 years	64.0	77.0
15 years - 20 years	91.0	78.0
20 years+	537.0	531.0
Total	2,914.0	2,495.0
Entergy Arkansas [Member]
Fair value of debt securities by contractual maturities
Less than 1 year	59.5	32.5
1 year - 5 years	143.2	170.3
5 years - 10 years	129.0	114.0
10 years - 15 years	11.1	10.3
15 years - 20 years	9.7	8.1
20 years+	49.1	46.1
Total	401.6	381.3
Entergy Louisiana [Member]
Fair value of debt securities by contractual maturities
Less than 1 year	52.5	31.1
1 year - 5 years	128.7	130.5
5 years - 10 years	134.4	111.0
10 years - 15 years	27.6	29.0
15 years - 20 years	44.3	37.1
20 years+	188.8	194.2
Total	576.3	532.9
System Energy [Member]
Fair value of debt securities by contractual maturities
Less than 1 year	11.3	22.8
1 year - 5 years	197.6	188.0
5 years - 10 years	90.5	73.4
10 years - 15 years	1.7	5.2
15 years - 20 years	3.2	10.2
20 years+	82.3	64.6
Total	$ 386.6	$ 364.2