Risk Management and Fair Values (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 Y	Mar. 31, 2012	Dec. 31, 2012
Risk Management and Fair Values [Abstract]
Derivative, Collateral, Obligation to Return Cash	$ 12		$ 56
Cash flow hedges relating to power sales as part of net unrealized gains	15
Reclassified from accumulated other comprehensive income (OCI) to operating revenues	5
Maturity of cash flow hedges, before taxes	(2)	71
Maturity of cash flow hedges, Tax	(1)	25
Maximum length of time over which Company is currently hedging the variability in future cash flows for forecasted power transactions, years	1.75
Planned generation sold forward from non utility nuclear power plants in the next three quarters	84.00%
Planned Generation Sold Forward under financial derivatives	51.00%
Change in cash flow hedges due to ineffectiveness	(1.3)	0.2
Dollar amount of hedge contract in a liability position	25
Total volume of natural gas swaps outstanding (MMBtu)	60,540,000
Cash flow hedges in-the-money contracts	77
Cash flow hedges out-of-money contracts	$ 25
Entergy Gulf States Louisiana [Member]
Risk Management and Fair Values [Abstract]
Total volume of natural gas swaps outstanding (MMBtu)	18,270,000
Entergy Louisiana [Member]
Risk Management and Fair Values [Abstract]
Total volume of natural gas swaps outstanding (MMBtu)	25,140,000
Entergy Mississippi [Member]
Risk Management and Fair Values [Abstract]
Total volume of natural gas swaps outstanding (MMBtu)	17,130,000