Decommissioning Trust Funds (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) counterparty	Dec. 31, 2016 USD ($) counterparty	Dec. 31, 2015 USD ($)	Mar. 31, 2017 USD ($)	Jan. 31, 2017 USD ($)
Decommissioning Fund Investments	$ 7,211,993	$ 5,723,897
Number of Derivative Contract Counterparties in a Liability Position | counterparty	8	3
Decommissioning Trust Funds [Abstract]
Deferred taxes on unrealized gains/(losses) recorded in OCI for non-regulated decommissioning trusts	$ 479,000	$ 399,000
Amortized cost of debt securities	$ 2,539,000	2,212,000
Average coupon rate of debt securities	3.24%
Proceeds from the dispositions of debt securities	$ 3,163,000	2,409,000	$ 2,492,000
Gains from dispositions of debt securities, gross	149,000	32,000	72,000
Losses from dispositions of debt securities, gross	$ 13,000	13,000	13,000
Average Duration of Debt Securities in Years	6 years 3 months 31 days
Average Maturity of Debt Securities, Years	9 years 11 months 26 days
Hedge Contracts In Liability Position	$ 65,000	8,000
Entergy Arkansas [Member]
Decommissioning Fund Investments	944,890	834,735
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	$ 349,100	310,100
Average coupon rate of debt securities	2.64%
Proceeds from the dispositions of debt securities	$ 339,400	197,400	213,000
Gains from dispositions of debt securities, gross	17,700	1,800	5,900
Losses from dispositions of debt securities, gross	$ 600	800	300
Average Duration of Debt Securities in Years	5 years 6 months 40 days
Average Maturity of Debt Securities, Years	7 years
Entergy Louisiana [Member]
Decommissioning Fund Investments	$ 1,312,073	1,140,707
Percentage Interest in River Bend	30.00%
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	$ 490,000	421,900
Average coupon rate of debt securities	3.88%
Proceeds from the dispositions of debt securities	$ 231,300	219,200	123,500
Gains from dispositions of debt securities, gross	12,000	3,900	1,900
Losses from dispositions of debt securities, gross	$ 400	400	300
Average Duration of Debt Securities in Years	6 years 2 months 3 days
Average Maturity of Debt Securities, Years	11 years 12 months 22 days
System Energy [Member]
Decommissioning Fund Investments	$ 905,686	780,496
Decommissioning Trust Funds [Abstract]
Amortized cost of debt securities	$ 327,500	309,100
Average coupon rate of debt securities	2.67%
Proceeds from the dispositions of debt securities	$ 565,400	499,300	390,400
Gains from dispositions of debt securities, gross	1,400	3,500	3,300
Losses from dispositions of debt securities, gross	$ 3,300	1,700	$ 500
Average Duration of Debt Securities in Years	6 years 5 months 23 days
Average Maturity of Debt Securities, Years	9 years 2 months 20 days
Indian Point 3 [Member]
Decommissioning Fund Investments	$ 798,000	719,000			$ 726,000
FitzPatrick [Member]
Decommissioning Fund Investments		785,000		$ 805,000	$ 793,000
Indian Point 1 [Member]
Decommissioning Fund Investments	491,000	443,000
Indian Point 2 [Member]
Decommissioning Fund Investments	621,000	564,000
Palisades [Member]
Decommissioning Fund Investments	458,000	412,000
Pilgrim [Member]
Decommissioning Fund Investments	1,068,000	960,000
Vermont Yankee [Member]
Decommissioning Fund Investments	$ 613,000	$ 584,000