Environmental Matters (details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014		Sep. 30, 2014		Dec. 31, 2013		Nov. 01, 2013	Sep. 30, 2013
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	$ 80,567		$ 80,567		$ 81,895			$ 48,517
Environmental Current Liabilities	10,653		10,653		16,176			5,384
Environmental Regulatory Table [Abstract]
Cash Paid for Environmental Sites	111,367	[1]	111,367	[1]	98,817	[1]		93,264	[1]
Regulatory Assets, Noncurrent	263,321		263,321		369,603			387,676
Utility Plant reclass- water treatment station							20,400
Environmental Remediation Obligations [Abstract]
Damages Sought On Environmental Claims			50,000
Environmental Settlement Insurance Payments Received To Date	150,000		150,000		48,000
Environmental settlement insurance payments received			102,000
Portland Harbor draft FS range			$169 million to $1.8 billion
Portland Harbor Number Of Potentially Responsible Parties			more than 100
Gasco Siltronic Sediments draft EE/CA range			$39.3 million to $350 million
Gasco Siltronic Sediments Project Liability	39,300		39,300
Gasco Groundwater Source Control construction costs			19,000
Gasco Groundwater Source Control Allocated Insurance Proceeds To Constructed Water Treatment Station	2,500
Gasco Siltronic Sediments [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	38,593		38,593		37,954			38,034
Environmental Current Liabilities	686		686		1,278			512
Portland Harbor Other [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	3,198		3,198		3,478			2,315
Environmental Current Liabilities	1,060		1,060		1,766			1,812
Gasco Upland [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	37,748		37,748		39,508			7,126
Environmental Current Liabilities	7,399		7,399		11,010			2,094
Siltronic Upland [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	577		577		406			434
Environmental Current Liabilities	634		634		763			405
Central Service Center [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	173		173		248			271
Environmental Current Liabilities	70		70		85			150
Front Street [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	99		99		122			158
Environmental Current Liabilities	804		804		1,274			411
Oregon Steel Mills [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	179		179		179			179
Environmental Current Liabilities	0		0		0			0
Environmental Restoration Costs [Member]
Environmental Regulatory Table [Abstract]
Regulatory Assets, Noncurrent	$ 51,861	[2],[3]	$ 51,861	[2],[3]	$ 148,389	[2],[3]		$ 118,029	[2],[3]

[1] Includes $20.4 million reclassified to utility plant on November 1, 2013 associated with the water treatment station of which a portion was paid during 2012 through 2014.

[2] Environmental costs relate to specific sites approved for regulatory deferral by the Public Utility Commission of Oregon (OPUC) and Washington Utilities and Transportation Commission (WUTC). In Oregon, we earn a carrying charge on cash amounts paid, whereas amounts accrued but not yet paid do not earn a carrying charge until expended. In Washington, a carrying charge related to deferred amounts will be determined in a future proceeding. For further information on environmental matters, see Note 13.

[3] Includes cash paid, remaining liability, and interest, net of insurance reimbursement and amounts reclassified to utility plant for the water treatment station.