Commitments and Contingencies (details) (USD $)	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	$ 55,941,000	$ 52,506,000	$ 44,711,000
Environmental Current Liabilities	22,507,000	20,183,000	13,289,000
Environmental Remediation Obligations [Abstract]
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	$34 million to $350 million
Gasco Siltronic Sediments Project Liability	34,000,000
Gasco Siltronic Sediments Other Liability	11,400,000
Portland Harbor RIFS And NRD Liability	4,400,000
Gasco Upland Liability	8,700,000
Gasco Groundwater Source Control range	$16.8 million and $30 million
Gasco Source Control Liability	16,800,000
Wutc Environmental Deferral Start Date	January 26, 2011
Cumulative Environmental Costs Paid	69,600,000
Cumulative Environmental Costs Recognized Prior To Regulatory Order	4,900,000
Environmental Regulatory Assets Noncurrent	128,200,000
Environmental Insurance Recovery	50,000,000
Gasco Siltronic Sediments [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	43,628,000	35,797,000	30,604,000
Environmental Current Liabilities	1,748,000	1,614,000	1,490,000
Portland Harbor Other [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	3,186,000	7,066,000	5,122,000
Environmental Current Liabilities	1,188,000	1,893,000	2,174,000
Gasco Upland [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	7,453,000	8,900,000	7,447,000
Environmental Current Liabilities	18,018,000	14,092,000	8,899,000
Siltronic Upland [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	592,000	128,000	114,000
Environmental Current Liabilities	511,000	887,000	721,000
Other Liabilities	1,100,000
Central Service Center [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	445,000	495,000	530,000
Environmental Current Liabilities	100,000	0	5,000
Other Liabilities	500,000
Front Street [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	452,000	0	765,000
Environmental Current Liabilities	942,000	1,697,000	0
Other Liabilities	1,400,000
Other Environmental [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Noncurrent Liabilities	185,000	120,000	129,000
Environmental Current Liabilities	$ 0	$ 0	$ 0