Retirement And Other Postretirement Benefits (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results		$ 21,000	$ 108,000	$ 71,000	$ 148,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 91,800
Entergy Arkansas [Member]
Defined Benefit Plan Disclosure [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results		2,800	13,700	13,400	30,700
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Plan Assets, Contributions by Employer	17,373
Entergy Louisiana [Member]
Defined Benefit Plan Disclosure [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results		6,100	27,800	26,100	50,700
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Plan Assets, Contributions by Employer	19,510
Entergy Mississippi [Member]
Defined Benefit Plan Disclosure [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results		600	2,700	2,400	6,300
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Plan Assets, Contributions by Employer	4,194
Entergy New Orleans [Member]
Defined Benefit Plan Disclosure [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results		200	1,300	1,000	4,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Plan Assets, Contributions by Employer	2,061
Entergy Texas [Member]
Defined Benefit Plan Disclosure [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results		(200)	200	(1,100)	4,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Plan Assets, Contributions by Employer	3,873
System Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results		900	$ 6,200	$ 5,100	$ 10,200
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Plan Assets, Contributions by Employer	3,715
Subsequent Event [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year						$ 352,100
Subsequent Event [Member] | Entergy Arkansas [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year						64,062
Defined Benefit Plan Remaining Contributions To Be Made In Current Fiscal Year						46,689
Subsequent Event [Member] | Entergy Louisiana [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year						71,917
Defined Benefit Plan Remaining Contributions To Be Made In Current Fiscal Year						52,407
Subsequent Event [Member] | Entergy Mississippi [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year						14,933
Defined Benefit Plan Remaining Contributions To Be Made In Current Fiscal Year						10,739
Subsequent Event [Member] | Entergy New Orleans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year						7,250
Defined Benefit Plan Remaining Contributions To Be Made In Current Fiscal Year						5,189
Subsequent Event [Member] | Entergy Texas [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year						10,883
Defined Benefit Plan Remaining Contributions To Be Made In Current Fiscal Year						7,010
Subsequent Event [Member] | System Energy [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year						13,786
Defined Benefit Plan Remaining Contributions To Be Made In Current Fiscal Year						$ 10,071
Non Qualified Pension Plans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Net periodic benefit costs	8,900	4,600
Settlement Charge Associated With Out Of Plan Payment Of Lump Sum Benefits	4,400
Non Qualified Pension Plans [Member] | Entergy Arkansas [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Net periodic benefit costs	132	105
Settlement Charge Associated With Out Of Plan Payment Of Lump Sum Benefits	12
Non Qualified Pension Plans [Member] | Entergy Louisiana [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Net periodic benefit costs	50	48
Non Qualified Pension Plans [Member] | Entergy Mississippi [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Net periodic benefit costs	80	64
Non Qualified Pension Plans [Member] | Entergy New Orleans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Net periodic benefit costs	21	18
Non Qualified Pension Plans [Member] | Entergy Texas [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Net periodic benefit costs	$ 137	$ 127