Commitments and Contingencies Commitments And Contingencies (Narrative) (Details) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Regulatory Assets [Line Items]
Damages claim filed in demand for arbitration	$ 165
Entergy Mississippi [Member]
Regulatory Assets [Line Items]
Proceeds From Insurance Settlement, Operating and Investing Activities	27.8
Capital expense related to Baxter Wilson recovery	12.7
Operation and maintenance expense incurred for Baxter Wilson recovery	15.1
Entergy Arkansas [Member] | Subsequent Event [Member]
Regulatory Assets [Line Items]
Expected NRC inspection costs excluding remediation and response costs		$ 15	$ 35