Retirement And Other Postretirement Benefits (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 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		$ 30,000		$ 76,000	$ 101,000	$ 71,000	$ 148,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Plan Assets, Contributions by Employer			$ 315,600
Entergy Arkansas [Member]
Defined Benefit Plan Disclosure [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results		3,515		9,995	13,668	13,392	30,671
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Plan Assets, Contributions by Employer			51,982
Entergy Louisiana [Member]
Defined Benefit Plan Disclosure [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results		8,585		20,942	27,796	26,118	50,686
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Plan Assets, Contributions by Employer			58,363
Entergy Mississippi [Member]
Defined Benefit Plan Disclosure [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results		778		1,862	2,742	2,424	6,268
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Plan Assets, Contributions by Employer			12,203
Entergy New Orleans [Member]
Defined Benefit Plan Disclosure [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results		356		794	1,293	1,014	3,975
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Plan Assets, Contributions by Employer			5,938
Entergy Texas [Member]
Defined Benefit Plan Disclosure [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results		43		(194)	179	(1,054)	4,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Plan Assets, Contributions by Employer			9,323
System Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results		1,521		4,778	$ 6,190	$ 5,088	$ 10,213
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Plan Assets, Contributions by Employer			11,152
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								$ 383,500
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								12,080
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								71,919
Defined Benefit Plan Remaining Contributions To Be Made In Current Fiscal Year								13,556
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								2,730
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								1,312
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								1,560
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								$ 2,634
Non Qualified Pension Plans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Net periodic benefit costs	$ 4,200	15,800	19,700	28,900
Settlement Charge Associated With Out Of Plan Payment Of Lump Sum Benefits	212	11,600	7,000	15,500
Non Qualified Pension Plans [Member] | Entergy Arkansas [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Net periodic benefit costs	114	111	369	483
Settlement Charge Associated With Out Of Plan Payment Of Lump Sum Benefits	7	10	0	173
Non Qualified Pension Plans [Member] | Entergy Louisiana [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Net periodic benefit costs	42	46	138	141
Non Qualified Pension Plans [Member] | Entergy Mississippi [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Net periodic benefit costs	73	62	230	189
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	20	18	62	55
Non Qualified Pension Plans [Member] | Entergy Texas [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Net periodic benefit costs	$ 122	$ 124	529	$ 377
Settlement Charge Associated With Out Of Plan Payment Of Lump Sum Benefits			$ 139