Decommissioning Trust Funds (Securities Held) (Details) (USD $)	Jun. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Fair Value	$ 4,015,000,000	$ 3,788,000,000
Total Unrealized Gains	682,000,000	538,000,000
Total Unrealized Losses	8,000,000	19,000,000
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	2,328,000,000	2,129,000,000
Total Unrealized Gains	566,000,000	423,000,000
Total Unrealized Losses	4,000,000	14,000,000
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	1,687,000,000	1,659,000,000
Total Unrealized Gains	116,000,000	115,000,000
Total Unrealized Losses	4,000,000	5,000,000
Entergy Arkansas [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	575,500,000	541,700,000
Total Unrealized Gains	112,600,000	86,100,000
Total Unrealized Losses	200,000	800,000
Entergy Arkansas [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	355,300,000	329,400,000
Total Unrealized Gains	97,900,000	70,900,000
Total Unrealized Losses		400,000
Entergy Arkansas [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	220,200,000	212,300,000
Total Unrealized Gains	14,700,000	15,200,000
Total Unrealized Losses	200,000	400,000
Entergy Gulf States Louisiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	452,500,000	420,900,000
Total Unrealized Gains	75,400,000	56,100,000
Total Unrealized Losses	200,000	1,100,000
Entergy Gulf States Louisiana [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	269,500,000	238,700,000
Total Unrealized Gains	60,300,000	40,900,000
Total Unrealized Losses	100,000	800,000
Entergy Gulf States Louisiana [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	183,000,000	182,200,000
Total Unrealized Gains	15,100,000	15,200,000
Total Unrealized Losses	100,000	300,000
Entergy Louisiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	272,600,000	254,000,000
Total Unrealized Gains	50,300,000	38,500,000
Total Unrealized Losses	500,000	1,800,000
Entergy Louisiana [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	163,300,000	149,200,000
Total Unrealized Gains	40,800,000	29,700,000
Total Unrealized Losses	400,000	1,600,000
Entergy Louisiana [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	109,300,000	104,800,000
Total Unrealized Gains	9,500,000	8,800,000
Total Unrealized Losses	100,000	200,000
System Energy [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	459,800,000	423,400,000
Total Unrealized Gains	59,500,000	44,900,000
Total Unrealized Losses	1,100,000	5,500,000
System Energy [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	264,400,000	237,200,000
Total Unrealized Gains	51,000,000	35,400,000
Total Unrealized Losses	1,000,000	5,400,000
System Energy [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	195,400,000	186,200,000
Total Unrealized Gains	8,500,000	9,500,000
Total Unrealized Losses	$ 100,000	$ 100,000