Regulatory Matters Regulatory Matters (Decoupling and Earnings Sharing) (Details) - USD ($) $ in Thousands, number in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
OREGON | Revenue Subject to Refund [Member]
Schedule of Decoupling and Earnings Sharing [Line Items]
Regulatory Liabilities	$ 0	$ 0
OREGON | Decoupling [Member]
Schedule of Decoupling and Earnings Sharing [Line Items]
Regulatory Liabilities	(898)	(1,168)
IDAHO | Decoupling [Member]
Schedule of Decoupling and Earnings Sharing [Line Items]
Regulatory Assets	2,150	3,471
IDAHO | Revenue Subject to Refund [Member]
Schedule of Decoupling and Earnings Sharing [Line Items]
Regulatory Liabilities	$ (774)	(2,350)
WASHINGTON
Schedule of Decoupling and Earnings Sharing [Line Items]
Decoupling Maximum Rate Increase Request	0.00%
WASHINGTON | Decoupling [Member]
Schedule of Decoupling and Earnings Sharing [Line Items]
Regulatory Assets	$ 12,671	14,240
WASHINGTON | Revenue Subject to Refund [Member]
Schedule of Decoupling and Earnings Sharing [Line Items]
Regulatory Liabilities	$ (693)	$ (3,420)