Risk Management and Fair Values (Assets And Liabilities At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016
Assets at fair value on a recurring basis
Temporary cash investments		$ 725.0	$ 1,058.0
Available-for-sale Securities		7,212.0	5,724.0
Total		8,414.0	7,311.0
Liabilities at fair value on a recurring basis
Total		76.0
Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		6.0
Power Contracts Liabilities [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		70.0	11.0
Equity Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		526.0	480.0
Debt Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		2,550.0	2,213.0
Power Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		5.0	16.0
Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		45.0	46.0
Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		406.0	433.0
Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		21.0	21.0
Common trust funds valued using Net Asset Value [Domain]
Assets at fair value on a recurring basis
Available-for-sale Securities		4,136.0	3,031.0
Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities			13.0
Fair Value Inputs Level 1 [Member]
Assets at fair value on a recurring basis
Temporary cash investments		725.0	1,058.0
Total		2,827.0	3,015.0
Liabilities at fair value on a recurring basis
Total		6.0
Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		6.0
Fair Value Inputs Level 1 [Member] | Power Contracts Liabilities [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		0.0	0.0
Fair Value Inputs Level 1 [Member] | Equity Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		526.0	480.0
Fair Value Inputs Level 1 [Member] | Debt Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		1,125.0	985.0
Fair Value Inputs Level 1 [Member] | Power Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Fair Value Inputs Level 1 [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		45.0	46.0
Fair Value Inputs Level 1 [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		406.0	433.0
Fair Value Inputs Level 1 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities			13.0
Fair Value Inputs Level 2 [Member]
Assets at fair value on a recurring basis
Temporary cash investments		0.0	0.0
Total		1,425.0	1,228.0
Liabilities at fair value on a recurring basis
Total		0.0
Fair Value Inputs Level 2 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		0.0
Fair Value Inputs Level 2 [Member] | Power Contracts Liabilities [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		0.0	0.0
Fair Value Inputs Level 2 [Member] | Equity Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Fair Value Inputs Level 2 [Member] | Debt Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		1,425.0	1,228.0
Fair Value Inputs Level 2 [Member] | Power Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Fair Value Inputs Level 2 [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Fair Value Inputs Level 2 [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Fair Value Inputs Level 2 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Fair Value Inputs Level 2 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities			0.0
Fair Value Inputs Level 3 [Member]
Assets at fair value on a recurring basis
Temporary cash investments		0.0	0.0
Total		26.0	37.0
Liabilities at fair value on a recurring basis
Total		70.0
Fair Value Inputs Level 3 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		0.0
Fair Value Inputs Level 3 [Member] | Power Contracts Liabilities [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		70.0	11.0
Fair Value Inputs Level 3 [Member] | Equity Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Fair Value Inputs Level 3 [Member] | Debt Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Fair Value Inputs Level 3 [Member] | Power Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		5.0	16.0
Fair Value Inputs Level 3 [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Fair Value Inputs Level 3 [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Fair Value Inputs Level 3 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		21.0	21.0
Fair Value Inputs Level 3 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities			0.0
Entergy Mississippi [Member]
Assets at fair value on a recurring basis
Temporary cash investments		4.5	76.8
Total		38.6	114.1
Entergy Mississippi [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		1.2
Entergy Mississippi [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		32.0	31.8
Entergy Mississippi [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		2.1	3.2
Entergy Mississippi [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities			2.3
Entergy Mississippi [Member] | Fair Value Inputs Level 1 [Member]
Assets at fair value on a recurring basis
Temporary cash investments		4.5	76.8
Total		36.5	110.9
Entergy Mississippi [Member] | Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		1.2
Entergy Mississippi [Member] | Fair Value Inputs Level 1 [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		32.0	31.8
Entergy Mississippi [Member] | Fair Value Inputs Level 1 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Mississippi [Member] | Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities			2.3
Entergy Mississippi [Member] | Fair Value Inputs Level 2 [Member]
Assets at fair value on a recurring basis
Temporary cash investments		0.0	0.0
Total		0.0	0.0
Entergy Mississippi [Member] | Fair Value Inputs Level 2 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		0.0
Entergy Mississippi [Member] | Fair Value Inputs Level 2 [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Mississippi [Member] | Fair Value Inputs Level 2 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Mississippi [Member] | Fair Value Inputs Level 2 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities			0.0
Entergy Mississippi [Member] | Fair Value Inputs Level 3 [Member]
Assets at fair value on a recurring basis
Temporary cash investments		0.0	0.0
Total		2.1	3.2
Entergy Mississippi [Member] | Fair Value Inputs Level 3 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		0.0
Entergy Mississippi [Member] | Fair Value Inputs Level 3 [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Mississippi [Member] | Fair Value Inputs Level 3 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		2.1	3.2
Entergy Mississippi [Member] | Fair Value Inputs Level 3 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities			0.0
Entergy Louisiana [Member]
Assets at fair value on a recurring basis
Temporary cash investments		30.1	163.9
Available-for-sale Securities		1,312.1	1,140.7
Total		1,643.9	1,632.5
Entergy Louisiana [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		5.0
Entergy Louisiana [Member] | Equity Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	15.2	13.9
Entergy Louisiana [Member] | Debt Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	493.8	424.8
Entergy Louisiana [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		2.0	2.8
Entergy Louisiana [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		289.5	305.7
Entergy Louisiana [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		10.2	8.5
Entergy Louisiana [Member] | Common trust funds valued using Net Asset Value [Domain]
Assets at fair value on a recurring basis
Available-for-sale Securities	[2]	803.1	702.0
Entergy Louisiana [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities			10.9
Entergy Louisiana [Member] | Fair Value Inputs Level 1 [Member]
Assets at fair value on a recurring basis
Temporary cash investments		30.1	163.9
Total		480.1	629.5
Entergy Louisiana [Member] | Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		5.0
Entergy Louisiana [Member] | Fair Value Inputs Level 1 [Member] | Equity Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	15.2	13.9
Entergy Louisiana [Member] | Fair Value Inputs Level 1 [Member] | Debt Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	143.3	132.3
Entergy Louisiana [Member] | Fair Value Inputs Level 1 [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		2.0	2.8
Entergy Louisiana [Member] | Fair Value Inputs Level 1 [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		289.5	305.7
Entergy Louisiana [Member] | Fair Value Inputs Level 1 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Louisiana [Member] | Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities			10.9
Entergy Louisiana [Member] | Fair Value Inputs Level 2 [Member]
Assets at fair value on a recurring basis
Temporary cash investments		0.0	0.0
Total		350.5	292.5
Entergy Louisiana [Member] | Fair Value Inputs Level 2 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		0.0
Entergy Louisiana [Member] | Fair Value Inputs Level 2 [Member] | Equity Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	0.0	0.0
Entergy Louisiana [Member] | Fair Value Inputs Level 2 [Member] | Debt Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	350.5	292.5
Entergy Louisiana [Member] | Fair Value Inputs Level 2 [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Louisiana [Member] | Fair Value Inputs Level 2 [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Louisiana [Member] | Fair Value Inputs Level 2 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Louisiana [Member] | Fair Value Inputs Level 2 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities			0.0
Entergy Louisiana [Member] | Fair Value Inputs Level 3 [Member]
Assets at fair value on a recurring basis
Temporary cash investments		0.0	0.0
Total		10.2	8.5
Entergy Louisiana [Member] | Fair Value Inputs Level 3 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		0.0
Entergy Louisiana [Member] | Fair Value Inputs Level 3 [Member] | Equity Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	0.0	0.0
Entergy Louisiana [Member] | Fair Value Inputs Level 3 [Member] | Debt Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	0.0	0.0
Entergy Louisiana [Member] | Fair Value Inputs Level 3 [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Louisiana [Member] | Fair Value Inputs Level 3 [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Louisiana [Member] | Fair Value Inputs Level 3 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		10.2	8.5
Entergy Louisiana [Member] | Fair Value Inputs Level 3 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities			0.0
Entergy Texas [Member]
Assets at fair value on a recurring basis
Temporary cash investments		115.5	5.0
Total		156.6	45.6
Entergy Texas [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		37.7	37.5
Entergy Texas [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		3.4	3.1
Entergy Texas [Member] | Fair Value Inputs Level 1 [Member]
Assets at fair value on a recurring basis
Temporary cash investments		115.5	5.0
Total		153.2	42.5
Entergy Texas [Member] | Fair Value Inputs Level 1 [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		37.7	37.5
Entergy Texas [Member] | Fair Value Inputs Level 1 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Texas [Member] | Fair Value Inputs Level 2 [Member]
Assets at fair value on a recurring basis
Temporary cash investments		0.0	0.0
Total		0.0	0.0
Entergy Texas [Member] | Fair Value Inputs Level 2 [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Texas [Member] | Fair Value Inputs Level 2 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Texas [Member] | Fair Value Inputs Level 3 [Member]
Assets at fair value on a recurring basis
Temporary cash investments		0.0	0.0
Total		3.4	3.1
Entergy Texas [Member] | Fair Value Inputs Level 3 [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Texas [Member] | Fair Value Inputs Level 3 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		3.4	3.1
Entergy New Orleans [Member]
Assets at fair value on a recurring basis
Temporary cash investments		32.7	103.0
Total		118.3	194.6
Entergy New Orleans [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		0.0
Entergy New Orleans [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		1.5	1.7
Entergy New Orleans [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		81.9	88.6
Entergy New Orleans [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		2.2	1.1
Entergy New Orleans [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities			0.2
Entergy New Orleans [Member] | Fair Value Inputs Level 1 [Member]
Assets at fair value on a recurring basis
Temporary cash investments		32.7	103.0
Total		116.1	193.5
Entergy New Orleans [Member] | Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		0.0
Entergy New Orleans [Member] | Fair Value Inputs Level 1 [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		1.5	1.7
Entergy New Orleans [Member] | Fair Value Inputs Level 1 [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		81.9	88.6
Entergy New Orleans [Member] | Fair Value Inputs Level 1 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy New Orleans [Member] | Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities			0.2
Entergy New Orleans [Member] | Fair Value Inputs Level 2 [Member]
Assets at fair value on a recurring basis
Temporary cash investments		0.0	0.0
Total		0.0	0.0
Entergy New Orleans [Member] | Fair Value Inputs Level 2 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		0.0
Entergy New Orleans [Member] | Fair Value Inputs Level 2 [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy New Orleans [Member] | Fair Value Inputs Level 2 [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy New Orleans [Member] | Fair Value Inputs Level 2 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy New Orleans [Member] | Fair Value Inputs Level 2 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities			0.0
Entergy New Orleans [Member] | Fair Value Inputs Level 3 [Member]
Assets at fair value on a recurring basis
Temporary cash investments		0.0	0.0
Total		2.2	1.1
Entergy New Orleans [Member] | Fair Value Inputs Level 3 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Derivative liability, net		0.0
Entergy New Orleans [Member] | Fair Value Inputs Level 3 [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy New Orleans [Member] | Fair Value Inputs Level 3 [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy New Orleans [Member] | Fair Value Inputs Level 3 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		2.2	1.1
Entergy New Orleans [Member] | Fair Value Inputs Level 3 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities			0.0
Entergy Arkansas [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		944.9	834.7
Total		954.0	851.3
Entergy Arkansas [Member] | Equity Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	11.7	3.6
Entergy Arkansas [Member] | Debt Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	348.2	309.3
Entergy Arkansas [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		3.7	4.1
Entergy Arkansas [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		2.4	7.1
Entergy Arkansas [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		3.0	5.4
Entergy Arkansas [Member] | Common trust funds valued using Net Asset Value [Domain]
Assets at fair value on a recurring basis
Available-for-sale Securities	[2]	585.0	521.8
Entergy Arkansas [Member] | Fair Value Inputs Level 1 [Member]
Assets at fair value on a recurring basis
Total		133.6	127.3
Entergy Arkansas [Member] | Fair Value Inputs Level 1 [Member] | Equity Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	11.7	3.6
Entergy Arkansas [Member] | Fair Value Inputs Level 1 [Member] | Debt Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	115.8	112.5
Entergy Arkansas [Member] | Fair Value Inputs Level 1 [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		3.7	4.1
Entergy Arkansas [Member] | Fair Value Inputs Level 1 [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		2.4	7.1
Entergy Arkansas [Member] | Fair Value Inputs Level 1 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Arkansas [Member] | Fair Value Inputs Level 2 [Member]
Assets at fair value on a recurring basis
Total		232.4	196.8
Entergy Arkansas [Member] | Fair Value Inputs Level 2 [Member] | Equity Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	0.0	0.0
Entergy Arkansas [Member] | Fair Value Inputs Level 2 [Member] | Debt Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	232.4	196.8
Entergy Arkansas [Member] | Fair Value Inputs Level 2 [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Arkansas [Member] | Fair Value Inputs Level 2 [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Arkansas [Member] | Fair Value Inputs Level 2 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Arkansas [Member] | Fair Value Inputs Level 3 [Member]
Assets at fair value on a recurring basis
Total		3.0	5.4
Entergy Arkansas [Member] | Fair Value Inputs Level 3 [Member] | Equity Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	0.0	0.0
Entergy Arkansas [Member] | Fair Value Inputs Level 3 [Member] | Debt Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	0.0	0.0
Entergy Arkansas [Member] | Fair Value Inputs Level 3 [Member] | Securitization Recovery Trust Account [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Arkansas [Member] | Fair Value Inputs Level 3 [Member] | Escrow Accounts [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		0.0	0.0
Entergy Arkansas [Member] | Fair Value Inputs Level 3 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities		3.0	5.4
System Energy [Member]
Assets at fair value on a recurring basis
Temporary cash investments		287.1	245.1
Available-for-sale Securities		905.7	780.5
Total		1,192.8	1,025.6
System Energy [Member] | Equity Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	3.1	0.3
System Energy [Member] | Debt Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	330.5	306.6
System Energy [Member] | Common trust funds valued using Net Asset Value [Domain]
Assets at fair value on a recurring basis
Available-for-sale Securities	[2]	572.1	473.6
System Energy [Member] | Fair Value Inputs Level 1 [Member]
Assets at fair value on a recurring basis
Temporary cash investments		287.1	245.1
Total		477.4	493.7
System Energy [Member] | Fair Value Inputs Level 1 [Member] | Equity Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	3.1	0.3
System Energy [Member] | Fair Value Inputs Level 1 [Member] | Debt Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	187.2	248.3
System Energy [Member] | Fair Value Inputs Level 2 [Member]
Assets at fair value on a recurring basis
Temporary cash investments		0.0	0.0
Total		143.3	58.3
System Energy [Member] | Fair Value Inputs Level 2 [Member] | Equity Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	0.0	0.0
System Energy [Member] | Fair Value Inputs Level 2 [Member] | Debt Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	143.3	58.3
System Energy [Member] | Fair Value Inputs Level 3 [Member]
Assets at fair value on a recurring basis
Temporary cash investments		0.0	0.0
Total		0.0	0.0
System Energy [Member] | Fair Value Inputs Level 3 [Member] | Equity Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	0.0	0.0
System Energy [Member] | Fair Value Inputs Level 3 [Member] | Debt Securities [Member]
Assets at fair value on a recurring basis
Available-for-sale Securities	[1]	$ 0.0	$ 0.0

[1] (a)The decommissioning trust funds hold equity and fixed income securities. Equity securities are invested to approximate the returns of major market indices. Fixed income securities are held in various governmental and corporate securities. See Note 9 to the financial statements for additional information on the investment portfolios.

[2] (b)Common trust funds are not publicly quoted, and are valued by the fund administrators using net asset value as a practical expedient. Accordingly, these funds are not assigned a level in the fair value table. The fund administrator of these investments allows daily trading at the net asset value and trades settle at a later date.