Balance Sheet Components Schedule of Other Asssets and Other Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Other current assets:
Prepaid Expense, Current	$ 54	$ 50
Margin Deposit Assets	16	11
Assets from price risk management activities	20	6
Other	0	6
Other Assets, Current	90	73
Accrued expenses and other current liabilities:
Regulatory Liability, Current	36	31
Accrued employee compensation and benefits	66	60
Accrued interest payable	27	27
Dividends payable	34	31
Taxes Payable, Current	34	31
Other	71	61
Other Liabilities, Current	$ 268	$ 241