Decommissioning Trust Funds (Securities Held) (Details) - USD ($)	Jun. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Fair Value	$ 5,389,000,000	$ 5,371,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1,533,000,000	1,589,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	19,000,000	7,000,000
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	3,274,000,000	3,286,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1,482,000,000	1,513,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	1,000,000	1,000,000
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	2,115,000,000	2,085,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	51,000,000	76,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	18,000,000	6,000,000
Entergy Arkansas [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	776,700,000	769,900,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	250,900,000	255,100,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	2,100,000	1,100,000
Entergy Arkansas [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	475,100,000	487,300,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	246,300,000	248,900,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Entergy Arkansas [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	301,600,000	282,600,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	4,600,000	6,200,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	2,100,000	1,100,000
Entergy Gulf States Louisiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	644,600,000	637,700,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	186,400,000	189,500,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	1,700,000	300,000
Entergy Gulf States Louisiana [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	403,300,000	395,900,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	178,700,000	177,600,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Entergy Gulf States Louisiana [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	241,300,000	241,800,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	7,700,000	11,900,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	1,700,000	300,000
Entergy Louisiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	390,200,000	383,600,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	122,700,000	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	243,500,000	239,600,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	117,500,000	116,700,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Entergy Louisiana [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	146,700,000	144,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	5,200,000	6,900,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	800,000	400,000
System Energy [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	697,300,000	679,800,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	193,700,000	193,900,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	1,200,000	300,000
System Energy [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	433,800,000	424,500,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	189,300,000	188,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	100,000	0
System Energy [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	263,500,000	255,300,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	4,400,000	5,900,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	$ 1,100,000	$ 300,000