Vogtle Units No. 3 and No. 4 Construction Project - Narrative (Details) - Vogtle Units No. 3 & No. 4 $ in Millions	1 Months Ended		6 Months Ended	12 Months Ended
	Apr. 30, 2020	Aug. 31, 2018 USD ($)	Jun. 30, 2020 USD ($) unit	Dec. 31, 2008 unit MW
Public Utility Property Plant and Equipment
Ownership interest (as a percent)			30.00%
Total investment in additional Vogtle units			$ 5,500
Construction contingency estimate		$ 800	800
Estimated project-level construction contingency		$ 240
Allocated project level contingency			425
Allocated project level contingency from interest in project level budget			128
Excess project contingency, total			75
Ownership amount of excess project contingency			23
Additional construction contingency, total			250
Ownership amount of additional project level contingency			75
Company level contingency			325
Workforce reduction, percent	20.00%
Minimum
Public Utility Property Plant and Equipment
COVID related costs			150
Ownership amount of COVID related costs			45
Maximum
Public Utility Property Plant and Equipment
COVID related costs			250
Ownership amount of COVID related costs			$ 75
Ownership participation agreement
Public Utility Property Plant and Equipment
Number of additional nuclear units | unit			2
Ownership interest (as a percent)			30.00%
Project budget			$ 7,500
Project extension term			1 year
EPC Agreement | Westinghouse Electric Company LLC and Stone & Webster, Inc.
Public Utility Property Plant and Equipment
Number of nuclear units | unit				2
Generating capacity of each nuclear unit | MW				1,100
Services Agreement | Westinghouse Electric Company LLC and Stone & Webster, Inc.
Public Utility Property Plant and Equipment
Written notice period for termination of agreement			30 days
Global Amendments To Term Sheet
Public Utility Property Plant and Equipment
Percentage of costs disallowed for recovery			6.00%
Global Amendments To Term Sheet | Minimum
Public Utility Property Plant and Equipment
Percentage of ownership approval to change primary construction contractor			90.00%