Acquisitions and Dispositions (Schedule of Acquisitions of Solar Projects) (Details) $ in Millions		1 Months Ended			2 Months Ended			6 Months Ended
		Jun. 30, 2015 USD ($) project MW	Apr. 30, 2015 USD ($) project MW		Jul. 31, 2015 USD ($)	May 31, 2015 USD ($)		Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)
Business Acquisition [Line Items]
Acquisition of solar development projects								$ 0	$ 230
EC&R NA Solar PV, LLC
Business Acquisition [Line Items]
Number of Projects | project			1
Initial Acquisition Cost	[1]		$ 66
Acquisition of solar development projects	[2]					$ 66
MW Capacity | MW			20
EDF Renewable Development, Inc.
Business Acquisition [Line Items]
Number of Projects | project		1	3	[3]
Initial Acquisition Cost	[1]	$ 68	$ 106	[3]
Acquisition of solar development projects	[2]				$ 68	$ 106	[3]
MW Capacity | MW		18	24	[3]

[1] The purchase price was primarily allocated to Property, Plant and Equipment.

[2] Includes acquisition cost.

[3] One of the projects, Marin Carport, began commercial operations in 2016.