Balance Sheet Components Regulatory Assets and Liabilities (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current Regulatory Assets [Member]
Regulatory Assets and Liabilities [Line Items]
Price risk management	$ 14	$ 36
Pension and other postretirement plans	0	0
Deferred income taxes	0	0
Deferred broker settlements	7	12
Debt reacquisition costs	0	0
Deferred capital projects	8	16
Other	9	2
Total regulatory assets	38	66
Noncurrent Regulatory Assets [Member]
Regulatory Assets and Liabilities [Line Items]
Price risk management	78	140
Pension and other postretirement plans	185	194
Deferred income taxes	81	76
Deferred broker settlements	0	1
Debt reacquisition costs	16	17
Deferred capital projects	19	18
Other	20	18
Total regulatory assets	399	464
Current Regulatory Liabilities [Member]
Regulatory Assets and Liabilities [Line Items]
Asset retirement removal costs	0	0
Trojan decommissioning activities	0	0
Asset retirement obligations	0	0
Other	5	1
Total regulatory liabilities	5	1
Noncurrent Regulatory Liabilities [Member]
Regulatory Assets and Liabilities [Line Items]
Asset retirement removal costs	776	747
Trojan decommissioning activities	43	41
Asset retirement obligations	39	39
Other	55	38
Total regulatory liabilities	$ 913	$ 865