Revenue Recognition - Management Program (Details) - USD ($)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Vogtle Units No. 3 & No. 4
Operating revenues
Amounts billed under rate management program	$ 12,368,000	$ 7,897,000
Cumulative recovery of financing costs	78,685,000
Vogtle New Units
Operating revenues
Amounts billed under additional rate management program	35,069,000	$ 10,805,000
Cumulative recovery of financing costs	$ 50,505,000