Significant Accounting Policies (Depreciation Rates and Estimated Useful Life) (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Generation
Depreciation rates	2.62%	2.68%	2.59%
Generation | Virginia Electric and Power Company
Depreciation rates	2.62%	2.68%	2.59%
Transmission
Depreciation rates	2.17%	2.26%	2.24%
Transmission | Virginia Electric and Power Company
Depreciation rates	1.98%	2.03%	1.94%
Distribution
Depreciation rates	3.17%	3.19%	3.20%
Distribution | Virginia Electric and Power Company
Depreciation rates	3.32%	3.33%	3.33%
Storage
Depreciation rates	2.59%	2.64%	2.75%
Gas gathering and processing
Depreciation rates	2.49%	2.52%	2.39%
General and other
Depreciation rates	4.55%	4.66%	4.60%
General and other | Virginia Electric and Power Company
Depreciation rates	4.32%	4.38%	4.28%
Minimum | General and other
Property, Plant and Equipment, Useful Life	5 years
Minimum | Merchant generation-nuclear
Property, Plant and Equipment, Useful Life	34 years
Minimum | Merchant generation-other
Property, Plant and Equipment, Useful Life	27 years
Maximum | General and other
Property, Plant and Equipment, Useful Life	59 years
Maximum | Merchant generation-nuclear
Property, Plant and Equipment, Useful Life	44 years
Maximum | Merchant generation-other
Property, Plant and Equipment, Useful Life	40 years