Summary of Significant Accounting Policies (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Plant Farley [Member]
Accumulated Provisions for Decommissioning
Total	$ 563
Estimated Cost of Decommissioning
Beginning Year	2037
Completion Year	2065
Total site study costs	1,132
Plant Hatch [Member]
Accumulated Provisions for Decommissioning
Total	399
Estimated Cost of Decommissioning
Beginning Year	2034
Completion Year	2063
Total site study costs	629
Plant Vogtle [Member]
Accumulated Provisions for Decommissioning
Total	235
Estimated Cost of Decommissioning
Beginning Year	2047
Completion Year	2067
Total site study costs	571
Accumulated Provisions for Decommissioning External Trust Funds [Member] | Plant Farley [Member]
Accumulated Provisions for Decommissioning
Total	540
Accumulated Provisions for Decommissioning External Trust Funds [Member] | Plant Hatch [Member]
Accumulated Provisions for Decommissioning
Total	399
Accumulated Provisions for Decommissioning External Trust Funds [Member] | Plant Vogtle [Member]
Accumulated Provisions for Decommissioning
Total	235
Accumulated Provisions for Decommissioning Internal Reserves [Member] | Plant Farley [Member]
Accumulated Provisions for Decommissioning
Total	23
Accumulated Provisions for Decommissioning Internal Reserves [Member] | Plant Hatch [Member]
Accumulated Provisions for Decommissioning
Total	0
Accumulated Provisions for Decommissioning Internal Reserves [Member] | Plant Vogtle [Member]
Accumulated Provisions for Decommissioning
Total	0
Site Study Cost Radiated Structures [Member] | Plant Farley [Member]
Estimated Cost of Decommissioning
Total site study costs	1,060
Site Study Cost Radiated Structures [Member] | Plant Hatch [Member]
Estimated Cost of Decommissioning
Total site study costs	583
Site Study Cost Radiated Structures [Member] | Plant Vogtle [Member]
Estimated Cost of Decommissioning
Total site study costs	500
Site Study Cost Non-Radiated Structures [Member] | Plant Farley [Member]
Estimated Cost of Decommissioning
Total site study costs	72
Site Study Cost Non-Radiated Structures [Member] | Plant Hatch [Member]
Estimated Cost of Decommissioning
Total site study costs	46
Site Study Cost Non-Radiated Structures [Member] | Plant Vogtle [Member]
Estimated Cost of Decommissioning
Total site study costs	$ 71