Decommissioning Trust Funds (Securities Held) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Total	$ 2,495.0	$ 2,550.0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	19.0	44.0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	35.0	16.0
Debt Securities, Trading	389.0
Fair Value		7,212.0
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax		2,175.0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		17.0
Equity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value		4,662.0
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax		2,131.0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		1.0
Entergy Louisiana [Member]
Debt Securities, Available-for-sale [Line Items]
Total	532.9	493.8
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	4.1	10.9
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	6.0	3.6
Fair Value		1,312.1
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax		472.1
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		3.6
Entergy Louisiana [Member] | Equity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value		818.3
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax		461.2
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		0.0
Entergy Arkansas [Member]
Debt Securities, Available-for-sale [Line Items]
Total	381.3	348.2
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0.6	2.1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	8.2	3.0
Fair Value		944.9
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax		357.0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		3.0
Entergy Arkansas [Member] | Equity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value		596.7
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax		354.9
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		0.0
System Energy [Member]
Debt Securities, Available-for-sale [Line Items]
Total	364.2	330.5
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	2.9	4.2
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	$ 5.8	1.2
Fair Value		905.7
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax		312.8
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		1.2
System Energy [Member] | Equity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value		575.2
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax		308.6
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		$ 0.0