Transactions With Affiliates (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Entergy Arkansas [Member]
Intercompany revenues	$ 127.8	$ 49.4	$ 127.9
Intercompany operating expenses	510.2	467.4	508.5
Entergy Louisiana [Member]
Intercompany revenues	282.4	376.6	420.2
Intercompany operating expenses	619.5	670.8	929.4
Intercompany interest and investment income	128.0	127.7	133.6
Entergy Mississippi [Member]
Intercompany revenues	1.7	2.9	86.0
Intercompany operating expenses	310.5	256.5	331.8
Intercompany interest and investment income	0.0	0.1	0.0
Entergy New Orleans [Member]
Intercompany revenues	0.0	30.3	66.1
Intercompany operating expenses	286.1	276.7	278.4
Intercompany interest and investment income	0.2	0.0	0.0
Entergy Texas [Member]
Intercompany revenues	57.9	180.2	259.1
Intercompany operating expenses	234.6	343.7	413.7
System Energy [Member]
Intercompany revenues	633.5	548.3	632.4
Intercompany operating expenses	197.0	146.0	155.1
Intercompany interest and investment income	$ 0.9	$ 0.1	$ 0.0