Balance Sheet Components Electric Utility Plant, Net (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Amortization of Intangible Assets	$ 11	$ 10	$ 33	$ 28
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments	1		1
Capital Leases, Future Minimum Payments, Interest Included in Payments	1		1
Capital Leased Assets, Gross	57		57
Electric utility plant	9,415		9,415		$ 8,560
Construction work-in-progress	194		194		545
Total cost	9,609		9,609		9,105
Less: accumulated depreciation and amortization	(3,269)		(3,269)		(3,093)
Electric utility plant, net	6,340		6,340		$ 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	1		2
Capital Leases, Income Statement, Interest Expense	$ 1		$ 3