Commitments and Contingencies Commitments and Contingencies - Hydroelectric Relicensing (Details) (USD $) In Millions, unless otherwise specified			6 Months Ended		6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Klamath Hydroelectric System [Member]	Jun. 30, 2012 Klamath Hydroelectric System [Member] UTAH	Jun. 30, 2012 Klamath Hydroelectric System [Member] OREGON	Jun. 30, 2012 Klamath Hydroelectric System [Member] CALIFORNIA
Dam removal costs [Line Items]
Property, plant and equipment, net	$ 17,777	$ 17,374	$ 121	$ 36
Dam Removal Cost Limit			200		184	16
Additional Dam Removal Costs, California Bond Measure			$ 250