REGULATORY MATTERS: Oregon Jurisdiction Power Cost Adjustment Mechanism (Details) - Oregon Power Cost Adjustment - USD ($)	Jun. 01, 2015	Jun. 01, 2014	Jun. 01, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Oregon Jurisdiction Power Cost Adjustment Mechanism [Line Items]
Percentage to be Shared with Customers				90.00%
Percentage to be Shared with Entity				10.00%
Deviation from ROE Resulting in Collection or Refund for Actual Power Supply Costs				1.00%
Base Deferral Amount to be Collected					$ 0	$ 0
Approved Rate Increase (Decrease), Amount	$ (700,000)	$ 400,000	$ 2,900,000