Income Taxes Income Taxes (Reduction to Regulatory Liability Due to Return of Unprotected Excess ADIT (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	$ 96	$ 283	$ 219	$ 562
Entergy Arkansas [Member]
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	41	153	99	260
Entergy Louisiana [Member]
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	17	55	31	86
Entergy Mississippi [Member]
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	0	32	0	161
Entergy New Orleans [Member]
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	7	9	9	9
Entergy Texas [Member]
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	31	0	73	0
System Energy [Member]
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	$ 0	$ 34	$ 7	$ 46