Leases (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended														12 Months Ended				1 Months Ended	12 Months Ended
	Dec. 31, 2011 Ratio	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 Entergy Arkansas [Member]	Dec. 31, 2010 Entergy Arkansas [Member]	Dec. 31, 2009 Entergy Arkansas [Member]	Dec. 31, 2011 Entergy Gulf States Louisiana	Dec. 31, 2010 Entergy Gulf States Louisiana	Dec. 31, 2009 Entergy Gulf States Louisiana	Dec. 31, 2011 Entergy Mississippi	Dec. 31, 2010 Entergy Mississippi	Dec. 31, 2009 Entergy Mississippi	Dec. 31, 2011 Entergy Louisiana [Member]	Dec. 31, 2010 Entergy Louisiana [Member]	Dec. 31, 2011 Waterford 3 Lease Obligations [Member] Entergy Louisiana [Member] Transaction	Dec. 31, 1989 Waterford 3 Lease Obligations [Member] Entergy Louisiana [Member]	Dec. 31, 2011 Grand Gulf Lease Obligations [Member]	Dec. 31, 2010 Grand Gulf Lease Obligations [Member]	Oct. 31, 2007 Grand Gulf Lease Obligations [Member] System Energy [Member] Transaction	Dec. 31, 2011 Grand Gulf Lease Obligations [Member] System Energy [Member]	Dec. 31, 1988 Grand Gulf Lease Obligations [Member] System Energy [Member]
Sale Leaseback Transaction [Line Items]
Number of transactions under sale and leaseback															3				2
Operating lease payments and oil tank facilities lease payments				$ 8.3	$ 8.4	$ 7.2	$ 2.0	$ 2.3	$ 3.1	$ 3.4	$ 3.4	$ 3.4
Sale and leases back transaction amount																353.6					500.0
Interest of sale and lease back transaction																9.30%			11.50%
Implicit rate of future minimum lease payments															7.45%					5.13%
Expiration period of sale and lease back transaction															2017					2015
Net regulatory liability related to sale and leaseback transaction							30.3	24.9					62.6	52.9			(2.0)	60.6
Regulatory Assets																	0
Leases (Textual) [Abstract]
Total rental expense for leases	75.3	80.8	71.6
Value of non interest bearing first mortgage bonds	$ 208.2			$ 124.1
Minimum percentage of adjusted capitalization to be maintained as total equity capital	30.00%
Minimum fixed charge coverage ratio to be maintained	1.50
Rolling period of fixed charge coverage ratio	12 years