Risk Management and Fair Values (Assets And Liabilities At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, at Carrying Value	$ 923,194	$ 724,644
Assets at fair value on a recurring basis
Restricted Cash and Cash Equivalents, Current	58,000	45,000
Replacement Reserve Escrow	401,000	406,000
Equity Securities, FV-NI	1,569,000	526,000
Debt Securities	2,845,000	2,550,000
Available-for-sale Securities		7,212,000
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	8,856,000	8,414,000
Financial and Nonfinancial Liabilities, Fair Value Disclosure		76,000
Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis		6,000
Power Contracts Liabilities [Member]
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis	67,000
Common trust funds valued using Net Asset Value [Domain]
Assets at fair value on a recurring basis
Available-for-sale Securities	3,030,000	4,136,000
Power Contracts Assets [Member]
Assets at fair value on a recurring basis
Derivative Asset		5,000
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis		70,000
Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Derivative Asset	1,000
Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Derivative Asset	29,000	21,000
Fair Value Inputs Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, at Carrying Value	923,000	725,000
Assets at fair value on a recurring basis
Restricted Cash and Cash Equivalents, Current	58,000	45,000
Replacement Reserve Escrow	401,000	406,000
Equity Securities, FV-NI	1,569,000	526,000
Debt Securities	1,167,000	1,125,000
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	4,119,000	2,827,000
Financial and Nonfinancial Liabilities, Fair Value Disclosure		6,000
Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis		6,000
Fair Value Inputs Level 1 [Member] | Power Contracts Liabilities [Member]
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis	0
Fair Value Inputs Level 1 [Member] | Power Contracts Assets [Member]
Assets at fair value on a recurring basis
Derivative Asset		0
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis		0
Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Derivative Asset	1,000
Fair Value Inputs Level 1 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Derivative Asset	0	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
Assets at fair value on a recurring basis
Restricted Cash and Cash Equivalents, Current	0	0
Replacement Reserve Escrow	0	0
Equity Securities, FV-NI	0	0
Debt Securities	1,678,000	1,425,000
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	1,678,000	1,425,000
Financial and Nonfinancial Liabilities, Fair Value Disclosure		0
Fair Value, Inputs, Level 2 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis		0
Fair Value, Inputs, Level 2 [Member] | Power Contracts Liabilities [Member]
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis	0
Fair Value, Inputs, Level 2 [Member] | Power Contracts Assets [Member]
Assets at fair value on a recurring basis
Derivative Asset		0
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis		0
Fair Value, Inputs, Level 2 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Derivative Asset	0
Fair Value, Inputs, Level 2 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Derivative Asset	0	0
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
Restricted Cash and Cash Equivalents, Current	0	0
Replacement Reserve Escrow	0	0
Equity Securities, FV-NI	0	0
Debt Securities	0	0
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	29,000	26,000
Financial and Nonfinancial Liabilities, Fair Value Disclosure		70,000
Fair Value, Inputs, Level 3 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis		0
Fair Value, Inputs, Level 3 [Member] | Power Contracts Liabilities [Member]
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis	67,000
Fair Value, Inputs, Level 3 [Member] | Power Contracts Assets [Member]
Assets at fair value on a recurring basis
Derivative Asset		5,000
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis		70,000
Fair Value, Inputs, Level 3 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Derivative Asset	0
Fair Value, Inputs, Level 3 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Derivative Asset	29,000	21,000
Entergy Mississippi [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, at Carrying Value	7	4,489
Assets at fair value on a recurring basis
Replacement Reserve Escrow	32,300	32,000
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	36,400	38,600
Entergy Mississippi [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis		1,200
Entergy Mississippi [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Derivative Asset	0
Entergy Mississippi [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Derivative Asset	3,700	2,100
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		4,500
Assets at fair value on a recurring basis
Replacement Reserve Escrow	32,300	32,000
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	32,700	36,500
Entergy Mississippi [Member] | Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis		1,200
Entergy Mississippi [Member] | Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Derivative Asset	0
Entergy Mississippi [Member] | Fair Value Inputs Level 1 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets 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
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
Liabilities, Fair Value Disclosure on Recurring Basis		0
Entergy Mississippi [Member] | Fair Value, Inputs, Level 2 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Derivative Asset	0
Entergy Mississippi [Member] | Fair Value, Inputs, Level 2 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets 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
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	3,700	2,100
Entergy Mississippi [Member] | Fair Value, Inputs, Level 3 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis		0
Entergy Mississippi [Member] | Fair Value, Inputs, Level 3 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Derivative Asset	0
Entergy Mississippi [Member] | Fair Value, Inputs, Level 3 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Derivative Asset	3,700	2,100
Entergy Louisiana [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, at Carrying Value	213,222	30,071
Assets at fair value on a recurring basis
Restricted Cash and Cash Equivalents, Current	10,000	2,000
Replacement Reserve Escrow	288,100	289,500
Equity Securities, FV-NI	12,900	15,200
Debt Securities	520,500	493,800
Available-for-sale Securities		1,312,100
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	1,919,500	1,643,900
Entergy Louisiana [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis		5,000
Entergy Louisiana [Member] | Common trust funds valued using Net Asset Value [Domain]
Assets at fair value on a recurring basis
Available-for-sale Securities	861,800	803,100
Entergy Louisiana [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Derivative Asset	1,000
Entergy Louisiana [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Derivative Asset	12,000	10,200
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	213,200	30,100
Assets at fair value on a recurring basis
Restricted Cash and Cash Equivalents, Current	10,000	2,000
Replacement Reserve Escrow	288,100	289,500
Equity Securities, FV-NI	12,900	15,200
Debt Securities	157,900	143,300
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	683,100	480,100
Entergy Louisiana [Member] | Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis		5,000
Entergy Louisiana [Member] | Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Derivative Asset	1,000
Entergy Louisiana [Member] | Fair Value Inputs Level 1 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Derivative Asset	0	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
Assets at fair value on a recurring basis
Restricted Cash and Cash Equivalents, Current	0	0
Replacement Reserve Escrow	0	0
Equity Securities, FV-NI	0	0
Debt Securities	362,600	350,500
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	362,600	350,500
Entergy Louisiana [Member] | Fair Value, Inputs, Level 2 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis		0
Entergy Louisiana [Member] | Fair Value, Inputs, Level 2 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Derivative Asset	0
Entergy Louisiana [Member] | Fair Value, Inputs, Level 2 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Derivative Asset	0	0
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
Assets at fair value on a recurring basis
Restricted Cash and Cash Equivalents, Current	0	0
Replacement Reserve Escrow	0	0
Equity Securities, FV-NI	0	0
Debt Securities	0	0
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	12,000	10,200
Entergy Louisiana [Member] | Fair Value, Inputs, Level 3 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis		0
Entergy Louisiana [Member] | Fair Value, Inputs, Level 3 [Member] | Gas Hedge Contracts Assets [Member]
Assets at fair value on a recurring basis
Derivative Asset	0
Entergy Louisiana [Member] | Fair Value, Inputs, Level 3 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Derivative Asset	12,000	10,200
Entergy Arkansas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, at Carrying Value	208,661	32
Assets at fair value on a recurring basis
Restricted Cash and Cash Equivalents, Current	8,570	3,748
Replacement Reserve Escrow		2,400
Equity Securities, FV-NI	2,200	11,700
Debt Securities	378,500	348,200
Available-for-sale Securities		944,900
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	1,225,500	954,000
Entergy Arkansas [Member] | Common trust funds valued using Net Asset Value [Domain]
Assets at fair value on a recurring basis
Available-for-sale Securities	616,200	585,000
Entergy Arkansas [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Derivative Asset	11,300	3,000
Entergy Arkansas [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	208,700
Assets at fair value on a recurring basis
Restricted Cash and Cash Equivalents, Current	8,600	3,700
Replacement Reserve Escrow		2,400
Equity Securities, FV-NI	2,200	11,700
Debt Securities	111,000	115,800
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	330,500	133,600
Entergy Arkansas [Member] | Fair Value Inputs Level 1 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets 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]
Cash Equivalents, at Carrying Value	0
Assets at fair value on a recurring basis
Restricted Cash and Cash Equivalents, Current	0	0
Replacement Reserve Escrow		0
Equity Securities, FV-NI	0	0
Debt Securities	267,500	232,400
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	267,500	232,400
Entergy Arkansas [Member] | Fair Value, Inputs, Level 2 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets 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]
Cash Equivalents, at Carrying Value	0
Assets at fair value on a recurring basis
Restricted Cash and Cash Equivalents, Current	0	0
Replacement Reserve Escrow		0
Equity Securities, FV-NI	0	0
Debt Securities	0	0
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	11,300	3,000
Entergy Arkansas [Member] | Fair Value, Inputs, Level 3 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Derivative Asset	11,300	3,000
Entergy New Orleans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Temporary Cash Investments Fair Value	32,900
Cash Equivalents, at Carrying Value	32,894	32,711
Assets at fair value on a recurring basis
Restricted Cash and Cash Equivalents, Current	5,570	1,455
Replacement Reserve Escrow	80,400	81,900
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	121,000	118,300
Entergy New Orleans [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis		200
Entergy New Orleans [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Derivative Asset	2,100	2,200
Entergy New Orleans [Member] | Fair Value Inputs Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Temporary Cash Investments Fair Value	32,900
Cash Equivalents, at Carrying Value		32,700
Assets at fair value on a recurring basis
Restricted Cash and Cash Equivalents, Current	5,600	1,500
Replacement Reserve Escrow	80,400	81,900
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	118,900	116,100
Entergy New Orleans [Member] | Fair Value Inputs Level 1 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis		200
Entergy New Orleans [Member] | Fair Value Inputs Level 1 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets 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]
Temporary Cash Investments Fair Value	0
Cash Equivalents, at Carrying Value		0
Assets at fair value on a recurring basis
Restricted Cash and Cash Equivalents, Current	0	0
Replacement Reserve Escrow	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
Liabilities, Fair Value Disclosure on Recurring Basis		0
Entergy New Orleans [Member] | Fair Value, Inputs, Level 2 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets 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]
Temporary Cash Investments Fair Value	0
Cash Equivalents, at Carrying Value		0
Assets at fair value on a recurring basis
Restricted Cash and Cash Equivalents, Current	0	0
Replacement Reserve Escrow	0	0
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	2,100	2,200
Entergy New Orleans [Member] | Fair Value, Inputs, Level 3 [Member] | Gas Hedge Contracts [Member]
Liabilities at fair value on a recurring basis
Liabilities, Fair Value Disclosure on Recurring Basis		0
Entergy New Orleans [Member] | Fair Value, Inputs, Level 3 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Derivative Asset	2,100	2,200
Entergy Texas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, at Carrying Value	18,956	115,481
Assets at fair value on a recurring basis
Restricted Cash and Cash Equivalents, Current	33,675	37,683
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	52,800	156,600
Entergy Texas [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Derivative Asset	0	3,400
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	19,000	115,500
Assets at fair value on a recurring basis
Restricted Cash and Cash Equivalents, Current	33,700	37,700
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	52,700	153,200
Entergy Texas [Member] | Fair Value Inputs Level 1 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Derivative Asset	0	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	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	0
Entergy Texas [Member] | Fair Value, Inputs, Level 2 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Derivative Asset	0	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	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	3,400
Entergy Texas [Member] | Fair Value, Inputs, Level 3 [Member] | Fixed Transmission Rights (FTRs) [Member]
Assets at fair value on a recurring basis
Derivative Asset	0	3,400
System Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, at Carrying Value	254,388	287,109
Assets at fair value on a recurring basis
Equity Securities, FV-NI	7,400	3,100
Debt Securities	359,200	330,500
Available-for-sale Securities		905,700
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	1,206,800	1,192,800
System Energy [Member] | Common trust funds valued using Net Asset Value [Domain]
Assets at fair value on a recurring basis
Available-for-sale Securities	585,800	572,100
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	254,400	287,100
Assets at fair value on a recurring basis
Equity Securities, FV-NI	7,400	3,100
Debt Securities	211,100	187,200
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	472,900	477,400
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
Assets at fair value on a recurring basis
Equity Securities, FV-NI	0	0
Debt Securities	148,100	143,300
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	148,100	143,300
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
Assets at fair value on a recurring basis
Equity Securities, FV-NI	0	0
Debt Securities	0	0
Liabilities at fair value on a recurring basis
Assets, Fair Value Disclosure	$ 0	$ 0