Decommissioning Trust Funds (Securities Held) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Fair Value	$ 5,180.0	$ 4,903.0
Total Unrealized Gains	1,446.0	1,307.0
Total Unrealized Losses	11.0	29.0
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	3,174.0	3,073.0
Total Unrealized Gains	1,385.0	1,260.0
Total Unrealized Losses	1.0	0
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	2,006.0	1,830.0
Total Unrealized Gains	61.0	47.0
Total Unrealized Losses	10.0	29.0
Entergy Arkansas [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	745.1	710.9
Total Unrealized Gains	232.7	219.3
Total Unrealized Losses	2.1	5.2
Entergy Arkansas [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	462.8	463.3
Total Unrealized Gains	227.4	214.0
Total Unrealized Losses	0	0
Entergy Arkansas [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	282.3	247.6
Total Unrealized Gains	5.3	5.3
Total Unrealized Losses	2.1	5.2
Entergy Gulf States Louisiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	613.7	573.7
Total Unrealized Gains	171.8	149.2
Total Unrealized Losses	0.7	3.5
Entergy Gulf States Louisiana [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	379.5	370.8
Total Unrealized Gains	161.0	141.8
Total Unrealized Losses	0	0
Entergy Gulf States Louisiana [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	234.2	202.9
Total Unrealized Gains	10.8	7.4
Total Unrealized Losses	0.7	3.5
Entergy Louisiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	368.3	347.3
Total Unrealized Gains	111.8	100.8
Total Unrealized Losses	0.7	1.9
Entergy Louisiana [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	230.9	224.2
Total Unrealized Gains	106.3	96.1
Total Unrealized Losses	0	0
Entergy Louisiana [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	137.4	123.1
Total Unrealized Gains	5.5	4.7
Total Unrealized Losses	0.7	1.9
System Energy [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	650.7	603.9
Total Unrealized Gains	173.4	154.3
Total Unrealized Losses	0.6	1.8
System Energy [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	404.4	380.0
Total Unrealized Gains	169.2	150.8
Total Unrealized Losses	0	0
System Energy [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	246.3	223.9
Total Unrealized Gains	4.2	3.5
Total Unrealized Losses	$ 0.6	$ 1.8