Environmental Matters (details) (USD $)	9 Months Ended
	Sep. 30, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	$ 48,517,000		$ 45,235,000		$ 55,941,000
Environmental Current Liabilities	5,384,000		24,466,000		22,507,000
Environmental Regulatory Table [Abstract]
Cash Paid for Environmental Sites	93,264,000		71,124,000		64,709,000
Regulatory Assets, Noncurrent	387,676,000		382,255,000		362,472,000		362,290,000	364,132,000	367,536,000	325,692,000	323,371,000	343,085,000
Environmental Remediation Obligations [Abstract]
Damages Sought On Environmental Claims	50,000,000
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	$38.5 million to $350 million
Gasco Siltronic Sediments Project Liability	34,000,000
Gasco Siltronic Sediments Other Liability	4,500,000.0
Gasco Groundwater Source Control range	$0.3 million to $18 million
Gasco Groundwater Source Control construction costs	19,000,000
Gasco Siltronic Sediments [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	38,034,000		36,087,000		43,628,000
Environmental Current Liabilities	512,000		2,207,000		1,748,000
Portland Harbor Other [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	2,315,000		3,160,000		3,186,000
Environmental Current Liabilities	1,812,000		1,767,000		1,188,000
Gasco Upland [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	7,126,000		5,028,000		7,453,000
Environmental Current Liabilities	2,094,000		18,722,000		18,018,000
Siltronic Upland [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	434,000		379,000		592,000
Environmental Current Liabilities	405,000		637,000		511,000
Central Service Center [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	271,000		396,000		445,000
Environmental Current Liabilities	150,000		140,000		100,000
Front Street [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	158,000		0		452,000
Environmental Current Liabilities	411,000		993,000		942,000
Oregon Steel Mills [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	179,000		185,000		185,000
Environmental Current Liabilities	0		0		0
Environmental Restoration Costs [Member]
Environmental Regulatory Table [Abstract]
Regulatory Assets, Noncurrent	$ 118,029,000	[1],[2]	$ 121,144,000	[1],[2]	$ 123,178,000	[1],[2]

[1] Total regulatory asset deferral includes cash paid, remaining liability, and interest, net of insurance reimbursement.

[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 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. In our 2012 Oregon general rate case, the OPUC authorized a Site Remediation and Recovery Mechanism (SRRM) that allows the Company to recover prudently incurred environmental costs, subject to an earnings test. For further information on environmental matters, see Note 13 and Note 15.