Long - Term Debt Present Value of Future Minimum Lease Payments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Year One	$ 1,040,631
Year Two	2,460,563
Year Three	2,299,475
Year Four	1,379,140
Year Five	2,595,720
Long-term Debt, Fair Value	27,061,171	$ 24,813,818
Interest Expense, Debt	863,712	837,981	$ 807,382
Total Long-Term Debt	25,880,901	22,369,776
System Energy [Member]
Year One	50,305
Year Two	250,000
Year Three	36,100
Year Four	200,000
Year Five	0
Long-term Debt, Fair Value	743,040	840,540
Interest Expense, Debt	38,393	34,467	$ 35,328
Total Long-Term Debt	741,296	$ 805,274
Grand Gulf [Member] | System Energy [Member]
Year One	17,188
Year Two	17,188
Year Three	17,188
Year Four	17,188
Year Five	17,188
Long-term Debt, Maturities, Repayments of Principal after Year Five	171,875
Long-term Debt, Fair Value	257,815
Interest Expense, Debt	223,494
Total Long-Term Debt	$ 34,321