Decommissioning Trust Funds (Securities Held) (Details) - Debt Securities [Member] - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Fair Value	$ 2,462.0	$ 2,495.0
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	114.0	19.0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	2.0	35.0
Entergy Arkansas [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value	407.7	381.3
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	11.8	0.6
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0.9	8.2
Entergy Louisiana [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value	593.4	532.9
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	32.6	4.1
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0.3	6.0
System Energy [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value	395.3	364.2
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	19.7	2.9
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	$ 0.1	$ 5.8

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

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+ References

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