Transactions With Affiliates (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
RS Cogen [Member]
Intercompany Operating Expenses	$ 2.8	$ 41.1	$ 50.8
Entergy Arkansas [Member]
Intercompany Revenues	324.0	293.8	307.1
Intercompany Operating Expenses	580.7	752.7	545.6
Intercompany Interest and Investment Income	0	0.1	0.6
Entergy Arkansas [Member] | Entergy Power [Member]
Intercompany Operating Expenses	1.4	1.2	0.1
Entergy Gulf States Louisiana [Member]
Intercompany Revenues	380.6	574.5	462.9
Intercompany Operating Expenses	532.3	563.1	602.7
Intercompany Interest and Investment Income	28.2	32.5	26.5
Entergy Gulf States Louisiana [Member] | RS Cogen [Member]
Intercompany Operating Expenses	2.8	41.1	50.8
Entergy Louisiana [Member]
Intercompany Revenues	138.2	139.0	228.0
Intercompany Operating Expenses	597.4	574.0	483.0
Intercompany Interest and Investment Income	78.2	78.1	67.6
Entergy Louisiana [Member] | Entergy Power [Member]
Intercompany Operating Expenses	14.3	14.5	12.0
Entergy Mississippi [Member]
Intercompany Revenues	36.1	125.1	59.4
Intercompany Operating Expenses	352.7	337.2	372.9
Intercompany Interest and Investment Income	0	0.1	0.3
Entergy New Orleans [Member]
Intercompany Revenues	43.9	96.9	56.0
Intercompany Operating Expenses	247.2	226.6	235.8
Intercompany Interest and Investment Income	0	0.1	0.2
Entergy New Orleans [Member] | Entergy Power [Member]
Intercompany Operating Expenses	14.1	14.2	11.8
Entergy Texas [Member]
Intercompany Revenues	313.2	264.1	372.8
Intercompany Operating Expenses	386.1	486.6	519.0
Intercompany Interest and Investment Income	0.1	0	0.1
System Energy [Member]
Intercompany Revenues	622.1	563.4	558.6
Intercompany Operating Expenses	147.4	131.5	122.7
Intercompany Interest and Investment Income	$ 0	$ 0.6	$ 0.7