Vogtle Units No. 3 and No. 4 Construction Project (Details)		1 Months Ended	3 Months Ended	12 Months Ended
	Mar. 29, 2017 USD ($)	Jan. 31, 2016 USD ($)	Mar. 31, 2017 USD ($) item	Dec. 31, 2008 USD ($) item MW	Apr. 11, 2017 USD ($)
Vogtle Units Number 3 And Number 4
Vogtle Units No. 3 and No. 4 Construction Project
Current investment			$ 3,432,000,000
Anticipated additional costs per month on failure to meet revised forecasted in-service dates			$ 20,000,000
Vogtle Units Number 3 And Number 4 | Ownership participation agreement
Vogtle Units No. 3 and No. 4 Construction Project
Number of nuclear units | item			2
Ownership interest (as a percent)			30.00%
Vogtle Units Number 3 And Number 4 | Engineering, Procurement and Construction Agreement (the EPC Agreement) | Westinghouse Electric Company LLC and Stone & Webster, Inc. (collectively, the Contractor)
Vogtle Units No. 3 and No. 4 Construction Project
Number of nuclear units | item				2
Generating capacity of each nuclear unit | MW				1,100
Vogtle Units Number 3 And Number 4 | Engineering, Procurement and Construction Agreement (the EPC Agreement) | Westinghouse Electric Company LLC and Stone & Webster, Inc. (collectively, the Contractor) | In the event of abandonment of work
Vogtle Units No. 3 and No. 4 Construction Project
Liquidated damages, as a percent of contract price				40.00%
Liquidated damages				$ 1,100,000,000
Vogtle Units Number 3 And Number 4 | Engineering, Procurement and Construction Agreement (the EPC Agreement) | Westinghouse Electric Company LLC and Stone & Webster, Inc. (collectively, the Contractor) | Maximum
Vogtle Units No. 3 and No. 4 Construction Project
Liquidated damages, as a percent of contract price				10.00%
Liquidated damages				$ 920,000,000
Additional capital cost under the provision				$ 75,000,000
Vogtle Units Number 3 And Number 4 | Engineering, Procurement and Construction Agreement (the EPC Agreement) | Westinghouse Electric Company LLC
Vogtle Units No. 3 and No. 4 Construction Project
Written notice period for non-renewal of letter of credit		60 days
Vogtle Units Number 3 And Number 4 | Interim Assessment Agreement
Vogtle Units No. 3 and No. 4 Construction Project
Liquidated damages	$ 141,000,000
Aggregate liability paid or accrued			$ 245,000,000
Vogtle Units Number 3 And Number 4 | Interim Assessment Agreement | The Contractor and WECTEC Staffing Services LLC
Vogtle Units No. 3 and No. 4 Construction Project
Liquidated damages	$ 470,000,000
Notice period for termination of agreement, number of business days	5 days
Amount paid for services, per week	$ 5,400,000
Toshiba Corporation
Vogtle Units No. 3 and No. 4 Construction Project
Shareholder's equity negative balance					$ 1,900,000,000
Toshiba Corporation | Vogtle Units Number 3 And Number 4 | Engineering, Procurement and Construction Agreement (the EPC Agreement) | Westinghouse Electric Company LLC
Vogtle Units No. 3 and No. 4 Construction Project
Letters of credit		$ 920,000,000