Leases (Future Minimum Lease Payments Sale Leaseback Transactions) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
System Energy [Member] | Grand Gulf [Member]
Minimum Lease Payments, Sale Leaseback Transactions, Next Twelve Months	$ 17,188
Year Two	17,188
Year Three	17,188
Year Four	17,188
Year Five	17,188
Years thereafter	240,625
Total	326,565
Less: Amount representing interest	292,209
Present value of net minimum lease payments	$ 34,356
Entergy Louisiana [Member] | Waterford 3 [Member]
Minimum Lease Payments, Sale Leaseback Transactions, Next Twelve Months		$ 57,500
Less: Amount representing interest		$ 2,300