Decommissioning Trust Funds (Fair Value Of Debt Securities By Contractual Maturities) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Fair value of debt securities by contractual maturities
Less than 1 year	$ 185.0	$ 199.0
1 year - 5 years	1,100.0	1,066.0
5 years - 10 years	609.0	544.0
10 years - 15 years	67.0	77.0
15 years - 20 years	95.0	78.0
20 years+	506.0	531.0
Total	2,562.0	2,495.0
Entergy Arkansas [Member]
Fair value of debt securities by contractual maturities
Less than 1 year	35.6	32.5
1 year - 5 years	163.7	170.3
5 years - 10 years	123.7	114.0
10 years - 15 years	10.2	10.3
15 years - 20 years	9.4	8.1
20 years+	48.4	46.1
Total	391.0	381.3
Entergy Louisiana [Member]
Fair value of debt securities by contractual maturities
Less than 1 year	42.4	31.1
1 year - 5 years	119.3	130.5
5 years - 10 years	135.7	111.0
10 years - 15 years	26.8	29.0
15 years - 20 years	44.5	37.1
20 years+	187.0	194.2
Total	555.7	532.9
System Energy [Member]
Fair value of debt securities by contractual maturities
Less than 1 year	14.5	22.8
1 year - 5 years	195.0	188.0
5 years - 10 years	80.1	73.4
10 years - 15 years	4.1	5.2
15 years - 20 years	10.2	10.2
20 years+	71.3	64.6
Total	$ 375.2	$ 364.2