Balance Sheet Components Schedule of Other Asssets and Other Liabilities (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other current assets:
Prepaid Expense, Current	$ 39	$ 38
Current deferred income tax asset	33	42
accrued sales tax refund	23	0	0
Margin Deposit Assets	11	9
Assets from price risk management activities	6	13
Other	3	1
Other Assets, Current	115	103
Accrued expenses and other current liabilities:
Regulatory Liability, Current	60	1
Accrued employee compensation and benefits	51	46
Accrued interest payable	26	23
Dividends payable	23	22
Taxes Payable, Current	22	21
Other	54	58
Other Liabilities, Current	$ 236	$ 171