Balance Sheet Components Electric Utility Plant, Net (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Derivative Liability, Fair Value of Collateral	$ 15
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments	2
Capital Leases, Future Minimum Payments, Interest Included in Payments	3
Capital Leased Assets, Gross	54
Electric utility plant	8,663	$ 8,560
Construction work-in-progress	647	545
Total cost	9,310	9,105
Less: accumulated depreciation and amortization	(3,150)	(3,093)
Electric utility plant, net	6,160	$ 6,012
Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation	1
Capital Lease Obligations, Current	2
Capital Lease Obligations, Noncurrent	51
Amortization of Leased Asset	1
Capital Leases, Income Statement, Interest Expense	$ 2