Decommissioning Trust Funds (Available For Sale Securities Continuous Unrealized Loss Position Fair Value) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	$ 5.0	$ 0
More than 12 months Fair Value	0	0
Total Fair Value	5.0	0
Less than 12 Months Gross Unrealized Losses	1.0	0
More than 12 Months Gross Unrealized Losses	0	0
Total Gross Unrealized Losses	1.0	0
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	627.0	892.0
More than 12 months Fair Value	82.0	60.0
Total Fair Value	709.0	952.0
Less than 12 Months Gross Unrealized Losses	10.0	24.0
More than 12 Months Gross Unrealized Losses	5.0	5.0
Total Gross Unrealized Losses	15.0	29.0
Entergy Arkansas [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	0.1	0
More than 12 months Fair Value	0	0
Total Fair Value	0.1	0
Less than 12 Months Gross Unrealized Losses	0	0
More than 12 Months Gross Unrealized Losses	0	0
Total Gross Unrealized Losses	0	0
Entergy Arkansas [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	115.4	153.2
More than 12 months Fair Value	21.9	6.9
Total Fair Value	137.3	160.1
Less than 12 Months Gross Unrealized Losses	1.8	4.8
More than 12 Months Gross Unrealized Losses	1.1	0.4
Total Gross Unrealized Losses	2.9	5.2
Entergy Gulf States Louisiana [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	0	0
More than 12 months Fair Value	0	0
Total Fair Value	0	0
Less than 12 Months Gross Unrealized Losses	0	0
More than 12 Months Gross Unrealized Losses	0	0
Total Gross Unrealized Losses	0	0
Entergy Gulf States Louisiana [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	70.1	91.9
More than 12 months Fair Value	5.7	4.6
Total Fair Value	75.8	96.5
Less than 12 Months Gross Unrealized Losses	1.4	3.1
More than 12 Months Gross Unrealized Losses	0.4	0.4
Total Gross Unrealized Losses	1.8	3.5
Entergy Louisiana [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	0	0
More than 12 months Fair Value	0	0
Total Fair Value	0	0
Less than 12 Months Gross Unrealized Losses	0	0
More than 12 Months Gross Unrealized Losses	0	0
Total Gross Unrealized Losses	0	0
Entergy Louisiana [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	35.7	38.3
More than 12 months Fair Value	2.1	1.7
Total Fair Value	37.8	40.0
Less than 12 Months Gross Unrealized Losses	1.0	1.7
More than 12 Months Gross Unrealized Losses	0.2	0.2
Total Gross Unrealized Losses	1.2	1.9
System Energy [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	0.1	0
More than 12 months Fair Value	0	0
Total Fair Value	0.1	0
Less than 12 Months Gross Unrealized Losses	0	0
More than 12 Months Gross Unrealized Losses	0	0
Total Gross Unrealized Losses	0	0
System Energy [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	88.3	121.7
More than 12 months Fair Value	1.4	0.9
Total Fair Value	89.7	122.6
Less than 12 Months Gross Unrealized Losses	0.6	1.7
More than 12 Months Gross Unrealized Losses	0.1	0.1
Total Gross Unrealized Losses	$ 0.7	$ 1.8