Environmental Matters (details) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012
Environmental Regulatory Table [Abstract]
Cash Paid for Environmental Sites	$ 98,817,000	[1]	$ 71,124,000	[1]
Environmental Regulatory Assets Noncurrent	148,389,000	[2]	121,144,000	[2]
Environmental Remediation Obligations [Abstract]
Damages Sought On Environmental Claims	50,000,000
Environmental Settlement Insurance Payments Expected in 2014	102,000,000
Environmental Settlement Insurance Proceeds Received To Date	48,000,000
Loss Contingency Range Of Possible Loss Portland Harbor	$169 million to $1.8 billion
Portland Harbor Number Of Potentially Responsible Parties	more than 100
Loss Contingency Range Of Possible Loss Gasco Siltronic	$39.2 million to $350 million
Gasco Siltronic Sediments Project Liability	39,200,000.0
Gasco Groundwater Source Control construction costs	19,000,000.0
Gasco Groundwater Source Control Allocated Insurance Proceeds To Constructed Water Treatment Station	2,500,000
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Current Liabilities	16,176,000		24,466,000
Environmental Noncurrent Liabilities	81,895,000		45,235,000
Gasco Siltronic Sediments [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Current Liabilities	1,278,000		2,207,000
Environmental Noncurrent Liabilities	37,954,000		36,087,000
Portland Harbor Other [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Current Liabilities	1,766,000		1,767,000
Environmental Noncurrent Liabilities	3,478,000		3,160,000
Gasco Upland [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Current Liabilities	11,010,000		18,722,000
Environmental Noncurrent Liabilities	39,508,000		5,028,000
Siltronic Upland [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Current Liabilities	763,000		637,000
Environmental Noncurrent Liabilities	406,000		379,000
Central Service Center [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Current Liabilities	85,000		140,000
Environmental Noncurrent Liabilities	248,000		396,000
Front Street [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Current Liabilities	1,274,000		993,000
Environmental Noncurrent Liabilities	122,000		0
Other Environmental [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Current Liabilities	0		0
Environmental Noncurrent Liabilities	$ 179,000		$ 185,000

[1] Includes $20.1 million reclassified to utility plant in 2013 associated with the water treatment station of which a portion was paid in 2012.

[2] Includes cash paid, remaining liability, and interest, net of insurance reimbursement