Income Taxes Income Taxes (Reduction to Regulatory Liability Due to Return of Unprotected Excess ADIT (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Entergy Arkansas [Member]
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	$ 25	$ 108	$ 57	$ 108
Entergy Louisiana [Member]
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	7	31	14	31
Entergy Mississippi [Member]
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	0	129	0	129
Entergy New Orleans [Member]
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	2	0	2	0
Entergy Texas [Member]
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	20	0	42	0
System Energy [Member]
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	$ 7	$ 11	$ 7	$ 11