Income Taxes Income Taxes (Reduction to Regulatory Liability Due to Return of Unprotected Excess ADIT (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	$ 41	$ 30
Entergy Arkansas [Member]
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	8	13
Entergy Louisiana [Member]
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	8	8
Entergy New Orleans [Member]
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	0	3
Entergy Texas [Member]
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	7	6
System Energy [Member]
Reduction to regulatory liability due to return of unprotected excess accumulated deferred income taxes	$ 18	$ 0