Leases Leases (Narrative) (Details) - USD ($)	1 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2016	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 31, 2019	Dec. 31, 2015	Dec. 31, 1989	Dec. 31, 1988
Short-term Lease, Cost		$ 15,000	$ 15,000
Operating Lease, Right-of-Use Asset		236,000,000	236,000,000
Operating and Finance Lease Right of Use Asset and Lease Liabilities at Implementation							$ 263,000,000
Operating Leases, Rent Expense, Net				$ 47,800,000	$ 53,100,000	$ 44,400,000
Finance Lease, Right-of-Use Asset		60,000,000	60,000,000
Entergy Arkansas [Member]
Operating Lease, Right-of-Use Asset		49,503,000	49,503,000
Operating and Finance Lease Right of Use Asset and Lease Liabilities at Implementation							59,000,000
Operating Leases, Rent Expense, Net				6,200,000	7,500,000	8,000,000.0
Payments For Railcar Operating Lease				2,800,000	4,000,000	3,400,000
Finance Lease, Right-of-Use Asset		11,094,000	11,094,000
Entergy Louisiana [Member]
Short-term Lease, Cost		15,000	15,000
Operating Lease, Right-of-Use Asset		34,248,000	34,248,000
Operating and Finance Lease Right of Use Asset and Lease Liabilities at Implementation							51,000,000
Operating Leases, Rent Expense, Net				$ 20,200,000	23,000,000.0	17,800,000
Percentage Of Capacity And Energy Purchased Under Purchased Power Agreement				50.00%
Cash payment representing the purchase price to acquire the undivided interests in Waterford 3	$ 60,000,000
Portion of Waterford 3 purchase price satisfied through issuance of debt	$ 52,000,000
Payments For Railcar Operating Lease				$ 400,000	300,000	300,000
Finance Lease, Right-of-Use Asset		16,795,000	16,795,000
Entergy Mississippi [Member]
Operating Lease, Right-of-Use Asset		18,149,000	18,149,000
Operating and Finance Lease Right of Use Asset and Lease Liabilities at Implementation							26,000,000
Operating Leases, Rent Expense, Net				4,600,000	5,600,000	4,000,000.0
Oil Tank Facilities Lease Payments				100,000	1,600,000	1,600,000
Finance Lease, Right-of-Use Asset		6,994,000	6,994,000
Entergy New Orleans [Member]
Operating Lease, Right-of-Use Asset		3,894,000	3,894,000
Operating and Finance Lease Right of Use Asset and Lease Liabilities at Implementation							7,000,000
Operating Leases, Rent Expense, Net				2,500,000	2,500,000	900,000
Finance Lease, Right-of-Use Asset		2,913,000	2,913,000
Entergy Texas [Member]
Operating Lease, Right-of-Use Asset		13,074,000	13,074,000
Operating and Finance Lease Right of Use Asset and Lease Liabilities at Implementation							$ 16,000,000
Operating Leases, Rent Expense, Net				$ 3,100,000	3,400,000	2,800,000
Percent of minimum payments				100.00%
Capacity expense under purchase power agreements accounted for as operating leases				$ 30,500,000	34,100,000	26,100,000
Finance Lease, Right-of-Use Asset		$ 5,515,000	$ 5,515,000
System Energy [Member]
Operating Leases, Rent Expense, Net				1,900,000	2,200,000	$ 1,600,000
Grand Gulf [Member] | System Energy [Member]
Sale Leaseback Transaction, Net Book Value										$ 500,000,000
Regulatory Assets				0
Regulatory Liabilities				$ 55,600,000	$ 55,600,000
Waterford Three [Member] | Entergy Louisiana [Member]
Liability related to undivided interests in Waterford 3								$ 62,700,000
Reduced liability related to undivided interests in Waterford 3								60,000,000
Reduction in liability related to undivided interest in Waterford 3 recorded as credit to interest expense								$ 2,700,000
Implicit Rate Of Future Minimum Lease Payments						8.09%
Minimum Lease Payments, Sale Leaseback Transactions						$ 57,500,000
Interest Portion of Minimum Lease Payments, Sale Leaseback Transactions						$ 2,300,000
Sale Leaseback Transaction, Net Book Value									$ 353,600,000