Decommissioning Trust Funds (Available For Sale Securities Continuous Unrealized Loss Position Fair Value) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	$ 13.0	$ 23.0
More than 12 months Fair Value	0.0	1.0
Total Fair Value	13.0	24.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	5.0	1.0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0.0	0.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	5.0	1.0
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	1,087.0	1,169.0
More than 12 months Fair Value	13.0	20.0
Total Fair Value	1,100.0	1,189.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	21.0	26.0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1.0	1.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	22.0	27.0
Entergy Arkansas [Member] \| Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	1.1	0.0
More than 12 months Fair Value	0.0	0.0
Total Fair Value	1.1	0.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0.0	0.0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0.0	0.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	0.0	0.0
Entergy Arkansas [Member] \| Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	150.5	146.7
More than 12 months Fair Value	0.0	0.0
Total Fair Value	150.5	146.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3.6	4.2
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0.0	0.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	3.6	4.2
Entergy Louisiana [Member] \| Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	1.6	0.0
More than 12 months Fair Value	0.0	0.0
Total Fair Value	1.6	0.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0.0	0.0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0.0	0.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	0.0	0.0
Entergy Louisiana [Member] \| Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	189.9	198.8
More than 12 months Fair Value	2.7	4.8
Total Fair Value	192.6	203.6
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	4.1	4.8
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0.2	0.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	4.3	5.0
System Energy [Member] \| Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	1.0	0.0
More than 12 months Fair Value	0.0	0.0
Total Fair Value	1.0	0.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0.0	0.0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0.0	0.1
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	0.0	0.1
System Energy [Member] \| Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	200.5	220.9
More than 12 months Fair Value	0.2	0.8
Total Fair Value	200.7	221.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3.3	4.4
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0.1	0.1
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 3.4	$ 4.5

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27337-111563

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27337-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Topic 320
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-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27290-111563

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27337-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Topic 320
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27290-111563

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27337-111563

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