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Risk Management and Fair Values (Assets And Liabilities At Fair Value On A Recurring Basis) (Details) - USD ($)
Dec. 31, 2018
Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value $ 424,285,000 $ 724,644,000
Equity Securities, FV-NI 1,686,000,000 526,000,000
Assets at fair value on a recurring basis    
Replacement Reserve Escrow 403,000,000 406,000,000
Restricted Cash and Cash Equivalents, Current 51,000,000 45,000,000
Liabilities at fair value on a recurring basis    
Total 35,000,000 76,000,000
Debt Securities 2,884,000,000 2,550,000,000
Available-for-sale Securities   7,212,000,000
Assets, Fair Value Disclosure 7,818,000,000 8,414,000,000
Gas Hedge Contracts [Member]    
Liabilities at fair value on a recurring basis    
Derivative liability, net 1,000,000 6,000,000
Common trust funds valued using Net Asset Value [Domain]    
Liabilities at fair value on a recurring basis    
Available-for-sale Securities 2,350,000,000 4,136,000,000
Power Contracts Assets [Member]    
Liabilities at fair value on a recurring basis    
Derivative liability, net 34,000,000 70,000,000
Derivative Asset 3,000,000 5,000,000
Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 15,000,000 21,000,000
Gas Hedge Contracts Assets [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 2,000,000  
Fair Value Inputs Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 424,000,000 725,000,000
Equity Securities, FV-NI 1,686,000,000 526,000,000
Assets at fair value on a recurring basis    
Replacement Reserve Escrow 403,000,000 406,000,000
Restricted Cash and Cash Equivalents, Current 51,000,000 45,000,000
Liabilities at fair value on a recurring basis    
Total 1,000,000 6,000,000
Debt Securities 1,259,000,000 1,125,000,000
Assets, Fair Value Disclosure 3,823,000,000 2,827,000,000
Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts [Member]    
Liabilities at fair value on a recurring basis    
Derivative liability, net 1,000,000 6,000,000
Fair Value Inputs Level 1 [Member] | Power Contracts Assets [Member]    
Liabilities at fair value on a recurring basis    
Derivative liability, net 0 0
Derivative Asset 0 0
Fair Value Inputs Level 1 [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 0 0
Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts Assets [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 0  
Fair Value Inputs Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 0 0
Equity Securities, FV-NI 0 0
Assets at fair value on a recurring basis    
Replacement Reserve Escrow 0 0
Restricted Cash and Cash Equivalents, Current 0 0
Liabilities at fair value on a recurring basis    
Total 0 0
Debt Securities 1,625,000,000 1,425,000,000
Assets, Fair Value Disclosure 1,627,000,000 1,425,000,000
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 Assets [Member]    
Liabilities at fair value on a recurring basis    
Derivative liability, net 0 0
Derivative Asset 0 0
Fair Value Inputs Level 2 [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 0 0
Fair Value Inputs Level 2 [Member] | Gas Hedge Contracts Assets [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 2,000,000  
Fair Value Inputs Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 0 0
Equity Securities, FV-NI 0 0
Assets at fair value on a recurring basis    
Replacement Reserve Escrow 0 0
Restricted Cash and Cash Equivalents, Current 0 0
Liabilities at fair value on a recurring basis    
Total 34,000,000 70,000,000
Debt Securities 0 0
Assets, Fair Value Disclosure 18,000,000 26,000,000
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 Assets [Member]    
Liabilities at fair value on a recurring basis    
Derivative liability, net 34,000,000 70,000,000
Derivative Asset 3,000,000 5,000,000
Fair Value Inputs Level 3 [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 15,000,000 21,000,000
Fair Value Inputs Level 3 [Member] | Gas Hedge Contracts Assets [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 0  
Entergy Mississippi [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 36,943,000 4,489,000
Assets at fair value on a recurring basis    
Replacement Reserve Escrow 32,400,000 32,000,000
Liabilities at fair value on a recurring basis    
Assets, Fair Value Disclosure 71,500,000 38,600,000
Entergy Mississippi [Member] | Gas Hedge Contracts [Member]    
Liabilities at fair value on a recurring basis    
Derivative liability, net   1,200,000
Entergy Mississippi [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 2,200,000 2,100,000
Entergy Mississippi [Member] | Fair Value Inputs Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 36,900,000 4,500,000
Assets at fair value on a recurring basis    
Replacement Reserve Escrow 32,400,000 32,000,000
Liabilities at fair value on a recurring basis    
Assets, Fair Value Disclosure 69,300,000 36,500,000
Entergy Mississippi [Member] | Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts [Member]    
Liabilities at fair value on a recurring basis    
Derivative liability, net   1,200,000
Entergy Mississippi [Member] | Fair Value Inputs Level 1 [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 0 0
Entergy Mississippi [Member] | Fair Value Inputs Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 0 0
Assets at fair value on a recurring basis    
Replacement Reserve Escrow 0 0
Liabilities at fair value on a recurring basis    
Assets, Fair Value Disclosure 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
Entergy Mississippi [Member] | Fair Value Inputs Level 2 [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 0 0
Entergy Mississippi [Member] | Fair Value Inputs Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 0 0
Assets at fair value on a recurring basis    
Replacement Reserve Escrow 0 0
Liabilities at fair value on a recurring basis    
Assets, Fair Value Disclosure 2,200,000 2,100,000
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
Entergy Mississippi [Member] | Fair Value Inputs Level 3 [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 2,200,000 2,100,000
Entergy Louisiana [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 43,112,000 30,071,000
Equity Securities, FV-NI 13,300,000 15,200,000
Assets at fair value on a recurring basis    
Replacement Reserve Escrow 289,500,000 289,500,000
Restricted Cash and Cash Equivalents, Current 4,000,000 2,000,000
Liabilities at fair value on a recurring basis    
Debt Securities 532,900,000 493,800,000
Available-for-sale Securities   1,312,100,000
Assets, Fair Value Disclosure 1,631,400,000 1,643,900,000
Entergy Louisiana [Member] | Gas Hedge Contracts [Member]    
Liabilities at fair value on a recurring basis    
Derivative liability, net 1,100,000 5,000,000
Entergy Louisiana [Member] | Common trust funds valued using Net Asset Value [Domain]    
Liabilities at fair value on a recurring basis    
Available-for-sale Securities 738,800,000 803,100,000
Entergy Louisiana [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 8,300,000 10,200,000
Entergy Louisiana [Member] | Gas Hedge Contracts Assets [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 1,900,000  
Entergy Louisiana [Member] | Fair Value Inputs Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 43,100,000 30,100,000
Equity Securities, FV-NI 13,300,000 15,200,000
Assets at fair value on a recurring basis    
Replacement Reserve Escrow 289,500,000 289,500,000
Restricted Cash and Cash Equivalents, Current 3,600,000 2,000,000
Liabilities at fair value on a recurring basis    
Debt Securities 162,000,000 143,300,000
Assets, Fair Value Disclosure 511,500,000 480,100,000
Entergy Louisiana [Member] | Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts [Member]    
Liabilities at fair value on a recurring basis    
Derivative liability, net 700,000 5,000,000
Entergy Louisiana [Member] | Fair Value Inputs Level 1 [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 0 0
Entergy Louisiana [Member] | Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts Assets [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 0  
Entergy Louisiana [Member] | Fair Value Inputs Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 0 0
Equity Securities, FV-NI 0 0
Assets at fair value on a recurring basis    
Replacement Reserve Escrow 0 0
Restricted Cash and Cash Equivalents, Current 0 0
Liabilities at fair value on a recurring basis    
Debt Securities 370,900,000 350,500,000
Assets, Fair Value Disclosure 372,800,000 350,500,000
Entergy Louisiana [Member] | Fair Value Inputs Level 2 [Member] | Gas Hedge Contracts [Member]    
Liabilities at fair value on a recurring basis    
Derivative liability, net 400,000 0
Entergy Louisiana [Member] | Fair Value Inputs Level 2 [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 0 0
Entergy Louisiana [Member] | Fair Value Inputs Level 2 [Member] | Gas Hedge Contracts Assets [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 1,900,000  
Entergy Louisiana [Member] | Fair Value Inputs Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 0 0
Equity Securities, FV-NI 0 0
Assets at fair value on a recurring basis    
Replacement Reserve Escrow 0 0
Restricted Cash and Cash Equivalents, Current 0 0
Liabilities at fair value on a recurring basis    
Debt Securities 0 0
Assets, Fair Value Disclosure 8,300,000 10,200,000
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] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 8,300,000 10,200,000
Entergy Louisiana [Member] | Fair Value Inputs Level 3 [Member] | Gas Hedge Contracts Assets [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 0  
Entergy Texas [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 30,000 115,481,000
Assets at fair value on a recurring basis    
Restricted Cash and Cash Equivalents, Current 40,200,000 37,700,000
Liabilities at fair value on a recurring basis    
Assets, Fair Value Disclosure   156,600,000
Entergy Texas [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative liability, net 500,000  
Entergy Texas [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset   3,400,000
Entergy Texas [Member] | Fair Value Inputs Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value   115,500,000
Assets at fair value on a recurring basis    
Restricted Cash and Cash Equivalents, Current 40,200,000 37,700,000
Liabilities at fair value on a recurring basis    
Assets, Fair Value Disclosure   153,200,000
Entergy Texas [Member] | Fair Value Inputs Level 1 [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative liability, net 0  
Entergy Texas [Member] | Fair Value Inputs Level 1 [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset   0
Entergy Texas [Member] | Fair Value Inputs Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value   0
Assets at fair value on a recurring basis    
Restricted Cash and Cash Equivalents, Current 0 0
Liabilities at fair value on a recurring basis    
Assets, Fair Value Disclosure   0
Entergy Texas [Member] | Fair Value Inputs Level 2 [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative liability, net 0.0  
Entergy Texas [Member] | Fair Value Inputs Level 2 [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset   0
Entergy Texas [Member] | Fair Value Inputs Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value   0
Assets at fair value on a recurring basis    
Restricted Cash and Cash Equivalents, Current 0 0
Liabilities at fair value on a recurring basis    
Assets, Fair Value Disclosure   3,400,000
Entergy Texas [Member] | Fair Value Inputs Level 3 [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative liability, net 500,000  
Entergy Texas [Member] | Fair Value Inputs Level 3 [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset   3,400,000
Entergy New Orleans [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 19,651,000 32,711,000
Assets at fair value on a recurring basis    
Replacement Reserve Escrow 80,900,000 81,900,000
Restricted Cash and Cash Equivalents, Current 2,200,000 1,500,000
Liabilities at fair value on a recurring basis    
Assets, Fair Value Disclosure 104,100,000 118,300,000
Entergy New Orleans [Member] | Gas Hedge Contracts [Member]    
Liabilities at fair value on a recurring basis    
Derivative liability, net 100,000 200,000
Entergy New Orleans [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 1,300,000 2,200,000
Entergy New Orleans [Member] | Fair Value Inputs Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 19,700,000 32,700,000
Assets at fair value on a recurring basis    
Replacement Reserve Escrow 80,900,000 81,900,000
Restricted Cash and Cash Equivalents, Current 2,200,000 1,500,000
Liabilities at fair value on a recurring basis    
Assets, Fair Value Disclosure 102,800,000 116,100,000
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 100,000 200,000
Entergy New Orleans [Member] | Fair Value Inputs Level 1 [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 0 0
Entergy New Orleans [Member] | Fair Value Inputs Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 0 0
Assets at fair value on a recurring basis    
Replacement Reserve Escrow 0 0
Restricted Cash and Cash Equivalents, Current 0 0
Liabilities at fair value on a recurring basis    
Assets, Fair Value Disclosure 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] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 0 0
Entergy New Orleans [Member] | Fair Value Inputs Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 0 0
Assets at fair value on a recurring basis    
Replacement Reserve Escrow 0 0
Restricted Cash and Cash Equivalents, Current 0 0
Liabilities at fair value on a recurring basis    
Assets, Fair Value Disclosure 1,300,000 2,200,000
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] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 1,300,000 2,200,000
Entergy Arkansas [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 1,000 32,000
Equity Securities, FV-NI 4,000,000 11,700,000
Assets at fair value on a recurring basis    
Replacement Reserve Escrow   2,400,000
Restricted Cash and Cash Equivalents, Current 4,700,000 3,700,000
Liabilities at fair value on a recurring basis    
Debt Securities 381,300,000 348,200,000
Available-for-sale Securities   944,900,000
Assets, Fair Value Disclosure 920,100,000 954,000,000
Entergy Arkansas [Member] | Common trust funds valued using Net Asset Value [Domain]    
Liabilities at fair value on a recurring basis    
Available-for-sale Securities 526,700,000 585,000,000
Entergy Arkansas [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 3,400,000 3,000,000
Entergy Arkansas [Member] | Fair Value Inputs Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Equity Securities, FV-NI 4,000,000 11,700,000
Assets at fair value on a recurring basis    
Replacement Reserve Escrow   2,400,000
Restricted Cash and Cash Equivalents, Current 4,700,000 3,700,000
Liabilities at fair value on a recurring basis    
Debt Securities 94,800,000 115,800,000
Assets, Fair Value Disclosure 103,500,000 133,600,000
Entergy Arkansas [Member] | Fair Value Inputs Level 1 [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 0 0
Entergy Arkansas [Member] | Fair Value Inputs Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Equity Securities, FV-NI 0 0
Assets at fair value on a recurring basis    
Replacement Reserve Escrow   0
Restricted Cash and Cash Equivalents, Current 0 0
Liabilities at fair value on a recurring basis    
Debt Securities 286,500,000 232,400,000
Assets, Fair Value Disclosure 286,500,000 232,400,000
Entergy Arkansas [Member] | Fair Value Inputs Level 2 [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 0 0
Entergy Arkansas [Member] | Fair Value Inputs Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Equity Securities, FV-NI 0 0
Assets at fair value on a recurring basis    
Replacement Reserve Escrow   0
Restricted Cash and Cash Equivalents, Current 0 0
Liabilities at fair value on a recurring basis    
Debt Securities 0 0
Assets, Fair Value Disclosure 3,400,000 3,000,000
Entergy Arkansas [Member] | Fair Value Inputs Level 3 [Member] | Financial Transmission Rights (FTRs) [Member]    
Liabilities at fair value on a recurring basis    
Derivative Asset 3,400,000 3,000,000
System Energy [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 95,617,000 287,109,000
Equity Securities, FV-NI 4,400,000 3,100,000
Liabilities at fair value on a recurring basis    
Debt Securities 364,200,000 330,500,000
Available-for-sale Securities   905,700,000
Assets, Fair Value Disclosure 965,100,000 1,192,800,000
System Energy [Member] | Common trust funds valued using Net Asset Value [Domain]    
Liabilities at fair value on a recurring basis    
Available-for-sale Securities 500,900,000 572,100,000
System Energy [Member] | Fair Value Inputs Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 95,600,000 287,100,000
Equity Securities, FV-NI 4,400,000 3,100,000
Liabilities at fair value on a recurring basis    
Debt Securities 224,500,000 187,200,000
Assets, Fair Value Disclosure 324,500,000 477,400,000
System Energy [Member] | Fair Value Inputs Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 0 0
Equity Securities, FV-NI 0 0
Liabilities at fair value on a recurring basis    
Debt Securities 139,700,000 143,300,000
Assets, Fair Value Disclosure 139,700,000 143,300,000
System Energy [Member] | Fair Value Inputs Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, at Carrying Value 0 0
Equity Securities, FV-NI 0 0
Liabilities at fair value on a recurring basis    
Debt Securities 0 0
Assets, Fair Value Disclosure $ 0 $ 0