Asset Retirement Obligations (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended		3 Months Ended
	Dec. 31, 2011	Mar. 31, 2011 System Energy [Member]	Dec. 31, 2011 Entergy Wholesale Commodities [Member]
Asset Retirement Obligations (Textual) [Abstract]
Reduction in decommissioning liability		$ 38.9	$ 34.1
Decommissioning expense net-of-tax			21
Asset representing estimate of present value of difference between stipulated contract amount for decommissioning less cost estimated in independent decommissioning cost study	$ 521.6