Balance Sheet Components Other Current Liabilities (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Accrued employee compensation and benefits	$ 36	$ 46
Accrued interest payable	33	23
Accrued taxes payable	30	21
Accrued dividends payable	20	21
Regulatory liabilities—current	11	12
Other	62	56
Total accrued expenses and other current liabilities	$ 192	$ 179