Contingencies and Regulatory Matters (Details) (Costs associated with design changes, delays in the project schedule and issuance of the combined construction permits and operating licenses, Vogtle Units No.3 and No.4, USD $)	Dec. 31, 2012
Costs associated with design changes, delays in the project schedule and issuance of the combined construction permits and operating licenses | Vogtle Units No.3 and No.4
Nuclear Construction
Contractor's estimated adjustment attributable to the entity	$ 280,000,000