Contingencies and Regulatory Matters (Details)				1 Months Ended	6 Months Ended
	Aug. 20, 2014 item	Jul. 28, 2014 item	Mar. 13, 2014 item	Apr. 30, 2008 item MW	Jun. 30, 2015 USD ($) item	May. 22, 2014 USD ($)	Dec. 31, 2008 USD ($)
Nuclear Construction
Number of Electric Distribution Cooperative Members					38
Vogtle Units Number 3 And Number 4
Nuclear Construction
Number of Westinghouse AP1000 nuclear generating units				2
Nominally rated generating capacity for each unit | MW				1,100
Aggregate Damages Under Initial Complaint And Amended Counterclaim | Vogtle Units Number 3 And Number 4
Nuclear Construction
Contractor's estimated adjustment attributable to the entity | $					$ 470,000,000
Costs Associated With Design Changes Delays In Project Schedule And Issuance Of Combined Construction Permits And Operating Licenses | Vogtle Units Number 3 And Number 4
Nuclear Construction
Contractor's estimated adjustment attributable to the entity | $					390,000,000		$ 280,000,000
Amended counterclaim associated with design changes, delays in Project Schedule and issuance of permits and operating licenses | Vogtle Units Number 3 And Number 4
Nuclear Construction
Contractor's estimated adjustment attributable to the entity | $					$ 78,000,000	$ 75,000,000
Patronage Capital Litigation
Nuclear Construction
Number of defendant members	2		3
Number of excluded members against whom defendant class action is certified		1
Number of Electric Distribution Cooperative Members		38
Number of former consumer members		4
Number of members in which the former consumer members filing the lawsuit belonged		4
Percentage of cooperatives total booked patronage capital		30.00%
Number of current consumer members	2
Number of plaintiffs	3
Patronage Capital Litigation | Maximum
Nuclear Construction
Period of revolving schedule to retire the patronage capital of former consumer-members		13 years
Period of revolving schedule to adopt policies to periodically retire the patronage capital of all consumer-members		13 years