Acquisitions and Dispositions (Schedule of Acquisitions of Solar Projects) (Details) $ in Millions		1 Months Ended
		Jul. 31, 2015 USD ($) Project MW	Jun. 30, 2015 USD ($) Project MW	Apr. 30, 2015 USD ($) Project MW		Dec. 31, 2014 USD ($) Project MW	Nov. 30, 2014 USD ($) Project MW	Mar. 31, 2014 USD ($) Project MW
Business Acquisition [Line Items]
Project Cost (millions)			$ 66
Recurrent Energy Development Holdings, LLC
Business Acquisition [Line Items]
Number of Projects | Project								6
Initial Acquisition Cost (millions)	[1]							$ 50
Project Cost (millions)	[2]							$ 428
MW Capacity | MW								139
CSI Project Holdco, LLC
Business Acquisition [Line Items]
Number of Projects | Project							1
Initial Acquisition Cost (millions)	[1]						$ 79
Project Cost (millions)	[2]						$ 79
MW Capacity | MW							20
EDF Renewable Development, Inc.
Business Acquisition [Line Items]
Number of Projects | Project			1	3		1
Initial Acquisition Cost (millions)	[1]		$ 68	$ 106	[3]	$ 71
Project Cost (millions)	[2]		$ 68	$ 109		$ 71
MW Capacity | MW			18	24		20
EC&R NA Solar PV, LLC
Business Acquisition [Line Items]
Number of Projects | Project				1
Initial Acquisition Cost (millions)	[1]			$ 66
Project Cost (millions)	[2]			$ 66
MW Capacity | MW				20
SunPeak Solar, LLC
Business Acquisition [Line Items]
Number of Projects | Project		1
Initial Acquisition Cost (millions)	[1]	$ 42
Project Cost (millions)	[2]	$ 69
MW Capacity | MW		20

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

[2] Includes acquisition cost.

[3] Marin Carport is expected to begin commercial operations in 2016.