Balance Sheet Components Schedule of Other Asssets and Other Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Other current assets:
Prepaid Expense, Current	$ 48	$ 43
Margin Deposit Assets	8	33
Assets from price risk management activities	18	10
Other	3	2
Other Assets, Current	77	88
Accrued expenses and other current liabilities:
Regulatory Liability, Current	51	55
Accrued employee compensation and benefits	52	51
Accrued interest payable	25	25
Dividends payable	30	28
Taxes Payable, Current	25	25
Other	71	75
Other Liabilities, Current	$ 254	$ 259