Commitments and Contingencies, Legal Contingencies (Details) (USD $)	3 Months Ended		6 Months Ended			13 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Pacific Northwest FERC Refund Proceeding [Member] Factor	Jun. 30, 2001 Pacific Northwest FERC Refund Proceeding [Member]
Legal Contingencies [Abstract]
Accrual for legal contingency					$ 0
Minimum amount of damages claimed by plaintiff					34,000,000
Sales to the City of Seattle	993,704,000	966,429,000	2,197,247,000	2,083,886,000		50,000,000
Estimated City of Seattle's claim for refunds not including interest					$ 28,000,000
Number of factors considered in assessment					2