Income Taxes (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended			3 Months Ended		12 Months Ended			1 Months Ended	3 Months Ended		12 Months Ended			1 Months Ended	3 Months Ended				12 Months Ended			12 Months Ended			12 Months Ended			12 Months Ended			12 Months Ended			12 Months Ended
	Jun. 30, 2012	Dec. 31, 2012	Dec. 31, 2010	Dec. 31, 2011	Dec. 31, 2012 Parent Company [Member]	Dec. 31, 2009 Parent Company [Member]	Dec. 31, 2010 Entergy Arkansas [Member]	Dec. 31, 2012 Entergy Arkansas [Member]	Dec. 31, 2011 Entergy Arkansas [Member]	Jun. 30, 2012 Entergy Gulf States Louisiana [Member]	Jun. 30, 2012 Entergy Gulf States Louisiana [Member]	Sep. 30, 2008 Entergy Gulf States Louisiana [Member]	Dec. 31, 2010 Entergy Gulf States Louisiana [Member]	Dec. 31, 2012 Entergy Gulf States Louisiana [Member]	Dec. 31, 2011 Entergy Gulf States Louisiana [Member]	Jun. 30, 2012 Entergy Louisiana [Member]	Dec. 31, 2012 Entergy Louisiana [Member]	Jun. 30, 2012 Entergy Louisiana [Member]	Sep. 30, 2011 Entergy Louisiana [Member]	Sep. 30, 2008 Entergy Louisiana [Member]	Dec. 31, 2012 Entergy Louisiana [Member]	Dec. 31, 2010 Entergy Louisiana [Member]	Dec. 31, 2011 Entergy Louisiana [Member]	Dec. 31, 2010 Entergy Mississippi [Member]	Dec. 31, 2012 Entergy Mississippi [Member]	Dec. 31, 2011 Entergy Mississippi [Member]	Dec. 31, 2010 Entergy New Orleans [Member]	Dec. 31, 2012 Entergy New Orleans [Member]	Dec. 31, 2011 Entergy New Orleans [Member]	Dec. 31, 2010 Entergy Texas [Member]	Dec. 31, 2012 Entergy Texas [Member]	Dec. 31, 2011 Entergy Texas [Member]	Dec. 31, 2010 System Energy [Member]	Dec. 31, 2012 System Energy [Member]	Dec. 31, 2011 System Energy [Member]	Dec. 31, 2012 U. K. Windfall Tax Issue [Member]	Dec. 31, 2008 Hurricane Rita [Member] Entergy Gulf States Louisiana [Member]	Dec. 31, 2008 Hurricane Rita [Member] Entergy Louisiana [Member]
Income Taxes [Line Items]
Reduction in taxable income relating to 2009 CAM settlement						$ 5,700,000,000
Increase in taxable income related to Louisiana Act 55 financing										104,000,000						129,000,000
Deferred tax asset relating to 2004 CAM settlement, net of interest charges					155,000,000
Additional tax depreciation relating to 2004 CAM settlement																	547,000,000
Increase in taxable income relating to 2004 CAM settlement					2,970,000,000
Total interest included in IRS notices of deficiency																																				102,000,000
Valuation allowance on the deferred tax assets related to state net operating loss carryovers		69,600,000
Valuation allowance on the deferred tax assets related to capital loss carryovers		13,600,000
Unrecognized tax benefits if recognized, would lower the effective income tax rates		203,000,000	605,000,000	521,000,000			200,000	600,000					129,600,000	44,000,000	107,900,000		92,400,000				92,400,000	286,700,000	281,300,000	5,300,000	3,900,000	3,800,000				6,000,000	8,600,000	7,300,000	12,100,000	3,500,000
Remaining balances of unrecognized tax benefits, effective income tax rates		3,968,000,000	4,345,000,000	3,867,000,000
Accrued income tax interest and penalties		146,300,000	45,000,000	99,000,000				21,800,000	11,400,000				9,700,000	33,100,000	14,400,000		900,000				900,000	3,300,000	800,000	1,600,000	2,400,000	1,700,000		100,000	2,400,000	100,000	700,000	100,000	8,200,000	33,200,000	18,500,000
Total tax included in IRS notices of deficiency																																				152,000,000
Total tax and interest associated with the issue																																				254,000,000
Income recognized for tax purpose under wholesale electric power purchase agreements		1,500,000,000
Gain recognized for income tax purpose on formation of a wholly-owned subsidiary		1,030,000,000
Future additional tax depreciation																					1,030,000,000
Reversal of deferred tax liabilities and liabilities for uncertain tax positions																			422,000,000
Regulatory charges																					199,000,000
Reduction in net operating loss carryover		2,500,000,000
Proceeds from the LA Act 55 financing												274,700,000								679,000,000
Income tax benefit resulting from Act 55 financing settlement	172,000,000										20,000,000							143,000,000
Regulatory charge resulting from tax settlement											28,000,000							137,000,000
Net-of-tax regulatory charge resulting from tax settlement											17,000,000							84,000,000
Regulatory Liabilities								12,200,000	16,400,000					22,000,000	30,300,000		9,200,000				9,200,000		62,600,000
Proceeds from LURC																																					274,700,000	679,000,000
Proceed from loan by LCDA to corporation LURC																																					274,700,000	679,000,000
Reduction in taxable income due to accounting changes			1,300,000,000				292,000,000						132,000,000									185,000,000		48,000,000			13,000,000			45,000,000			180,000,000
Adjustment 2009 CAM						$ 9,300,000,000