Income Taxes Income Taxes (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015
Income tax benefit resulting from 2006-2007 audit	$ 20
Entergy Arkansas [Member]
Income tax benefit resulting from 2006-2007 audit	4
Entergy Gulf States Louisiana [Member]
Income tax benefit resulting from 2006-2007 audit	5
Entergy Louisiana [Member]
Income tax benefit resulting from 2006-2007 audit	6
System Energy [Member]
Income tax benefit resulting from 2006-2007 audit	$ 1