Long - Term Debt Present Value of Future Minimum Lease Payments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Long-Term Debt, Maturity, Year One	$ 2,100,275
Long-Term Debt, Maturity, Year Two	1,546,940
Long-Term Debt, Maturity, Year Three	2,375,720
Long-Term Debt, Maturity, Year Four	916,965
Long-Term Debt, Maturity, Year Five	2,195,627
Long-Term Debt, Fair Value	22,489,174	$ 22,573,837
Interest Expense, Debt	1,046,164	940,060	$ 863,712
Long-Term Debt	25,107,896	25,932,549
System Energy [Member]
Long-Term Debt, Maturity, Year One	0
Long-Term Debt, Maturity, Year Two	221,500
Long-Term Debt, Maturity, Year Three	0
Long-Term Debt, Maturity, Year Four	90,000
Long-Term Debt, Maturity, Year Five	325,000
Long-Term Debt, Fair Value	696,168	702,473
Interest Expense, Debt	48,416	37,381	$ 38,393
Long-Term Debt	738,459	$ 777,905
Grand Gulf [Member] | System Energy [Member]
Long-Term Debt, Maturity, Year One	17,188
Long-Term Debt, Maturity, Year Two	17,188
Long-Term Debt, Maturity, Year Three	17,188
Long-Term Debt, Maturity, Year Four	17,188
Long-Term Debt, Maturity, Year Five	17,188
Long-Term Debt, Maturity, after Year Five	137,500
Long-Term Debt, Fair Value	223,440
Interest Expense, Debt	189,180
Long-Term Debt	$ 34,260