Balance Sheet Components Regulatory Assets and Liabilities (Details) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Regulatory Assets, Current [Member]
Regulatory Assets [Line Items]
Price risk management	$ 187	$ 175
Pension and other postretirement plans	0	0
Deferred income taxes	0	0
Deferred broker settlements	8	24
Renewable energy deferral	6	22
Debt reacquisition costs	0	0
Other	7	0
Total regulatory assets	208	221
Noncurrent Regulatory Assets [Member]
Regulatory Assets [Line Items]
Price risk management	147	185
Pension and other postretirement plans	205	213
Deferred income taxes	89	95
Deferred broker settlements	0	0
Renewable energy deferral	0	0
Debt reacquisition costs	21	23
Other	19	28
Total regulatory assets	481	544
Current Regulatory Liabilities [Member]
Regulatory Assets [Line Items]
Asset retirement removal costs	0	0
Asset retirement obligations	0	0
Power Cost Adjustment Mechanism	0	0
Regulatory treatment of income taxes (SB 408)	6	5
Trojan ISFSI pollution control tax credits	5	18
Other	1	2
Total regulatory liabilities	12	25
Noncurrent Regulatory Liabilities [Member]
Regulatory Assets [Line Items]
Asset retirement removal costs	626	588
Asset retirement obligations	35	33
Power Cost Adjustment Mechanism	17	0
Regulatory treatment of income taxes (SB 408)	1	9
Trojan ISFSI pollution control tax credits	6	4
Other	27	23
Total regulatory liabilities	$ 712	$ 657