Balance Sheet Components Electric Utility Plant, Net (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Amortization of Intangible Assets	$ 10	$ 9	$ 22	$ 18
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments	1		1
Capital Leases, Future Minimum Payments, Interest Included in Payments	2		2
Capital Leased Assets, Gross	57		57
Electric utility plant	8,743		8,743		$ 8,560
Construction work-in-progress	746		746		545
Total cost	9,489		9,489		9,105
Less: accumulated depreciation and amortization	(3,205)		(3,205)		(3,093)
Electric utility plant, net	6,284		6,284		$ 6,012
Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation	2		2
Capital Lease Obligations, Current	3		3
Capital Lease Obligations, Noncurrent	$ 52		52
Amortization of Leased Asset			2
Capital Leases, Income Statement, Interest Expense			$ 3