Decommissioning Trust Funds (Securities Held) (Details) - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Fair Value	$ 5,191,000,000	$ 5,371,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1,313,000,000	1,589,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	15,000,000	7,000,000
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	3,018,000,000	3,286,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1,252,000,000	1,513,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	3,000,000	1,000,000
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	2,173,000,000	2,085,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	61,000,000	76,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	12,000,000	6,000,000
Entergy Arkansas [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	746,500,000	769,900,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	216,600,000	255,100,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	1,800,000	1,100,000
Entergy Arkansas [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	443,400,000	487,300,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	209,900,000	248,900,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	400,000	0
Entergy Arkansas [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	303,100,000	282,600,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	6,700,000	6,200,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	1,400,000	1,100,000
Entergy Louisiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	376,400,000	383,600,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	105,500,000	123,600,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	800,000	400,000
Entergy Louisiana [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	225,100,000	239,600,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	99,200,000	116,700,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	200,000	0
Entergy Louisiana [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	151,300,000	144,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	6,300,000	6,900,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	600,000	400,000
System Energy [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	674,200,000	679,800,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	160,500,000	193,900,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	1,300,000	300,000
System Energy [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	398,800,000	424,500,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	156,600,000	188,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	400,000	0
System Energy [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	275,400,000	255,300,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	3,900,000	5,900,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	$ 900,000	$ 300,000