Organization, Basis of Presentation and Significant Accounting Policies (Details 3) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment
In service	$ 47,484	$ 44,228
Less - Accumulated depreciation	(14,150)	(13,280)
Property, plant and equipment in service net of accumulated provision for depreciation	33,334	30,948
Regulated Distribution
Property, Plant and Equipment
In service	23,973	23,098
Less - Accumulated depreciation	(6,759)	(6,514)
Property, plant and equipment in service net of accumulated provision for depreciation	17,214	16,584
Regulated Transmission
Property, Plant and Equipment
In service	6,634	5,564
Less - Accumulated depreciation	(1,595)	(1,511)
Property, plant and equipment in service net of accumulated provision for depreciation	5,039	4,053
Competitive Energy Services
Property, Plant and Equipment
In service	16,442	15,206
Less - Accumulated depreciation	(5,598)	(5,088)
Property, plant and equipment in service net of accumulated provision for depreciation	10,844	10,118
Other/Corporate
Property, Plant and Equipment
In service	435	360
Less - Accumulated depreciation	(198)	(167)
Property, plant and equipment in service net of accumulated provision for depreciation	$ 237	$ 193