Property, Plant and Equipment (Components of PP&E) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Electric generation, distribution assets and other	30,459,000,000	$ 30,596,000,000
Accumulated depreciation	(9,962,000,000)	(9,604,000,000)
Net electric generation and distribution assets and other	20,497,000,000	20,992,000,000
Net electronic generation and distribution assets and other related to held for sale business	0	1,200,000,000
Capitalized computer software, net	115,000,000	133,000,000
Electric generation and distribution facilities
Property, Plant and Equipment [Line Items]
Electric generation, distribution assets and other	27,488,000,000	27,619,000,000
Electric generation and distribution facilities | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	5 years
Electric generation and distribution facilities | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	68 years
Other buildings
Property, Plant and Equipment [Line Items]
Electric generation, distribution assets and other	1,694,000,000	1,726,000,000
Other buildings | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	5 years
Other buildings | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	53 years
Furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Electric generation, distribution assets and other	307,000,000	312,000,000
Furniture, fixtures and equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	2 years
Furniture, fixtures and equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	31 years
Other
Property, Plant and Equipment [Line Items]
Electric generation, distribution assets and other	970,000,000	$ 939,000,000
Other | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	1 year
Other | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	50 years