Commitments and Contingencies (details) (USD $)	3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
Accrual For Environmental Loss Contingencies [Abstract]
Other current liabilities	$ 41,503,000	$ 41,597,000	$ 38,433,000
Other non-current liabilities	79,461,000	76,265,000	67,514,000
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 and $350 million
Gasco Siltronic Sediments Project Liability	34,000,000
Gasco Siltronic Sediments Other Liability	12,100,000
Gasco Upland Liability	9,300,000
Gasco Groundwater Source Control range	$11 million and $30 million
Gasco Source Control Liability	11,600,000
Wutc Environmental Deferral Start Date	January 26, 2011
Cumulative Environmental Costs Recognized	129,700,000
Cumulative Environmental Costs Recognized Prior To Regulatory Order	4,900,000
Environmental Regulatory Assets Noncurrent	112,300,000
Environmental Insurance Recovery	50,000,000
Environmental Current Liabilities	18,665,000	20,183,000	16,672,000
Environmental Noncurrent Liabilities	56,414,000	52,506,000	43,784,000
Gasco Siltronic Sediments [Member]
Accrual For Environmental Loss Contingencies [Abstract]
Other current liabilities	2,459,000	1,614,000	1,049,000
Other non-current liabilities	43,655,000	35,797,000	29,996,000
Portland Harbor Other [Member]
Accrual For Environmental Loss Contingencies [Abstract]
Other current liabilities	1,400,000	1,893,000	2,314,000
Other non-current liabilities	3,547,000	7,066,000	5,829,000
Other Liabilities	4,900,000
Gasco [Member]
Accrual For Environmental Loss Contingencies [Abstract]
Other current liabilities	13,197,000	14,092,000	12,574,000
Other non-current liabilities	7,689,000	8,900,000	6,103,000
Siltronic Upland [Member]
Accrual For Environmental Loss Contingencies [Abstract]
Other current liabilities	478,000	887,000	730,000
Other non-current liabilities	588,000	128,000	291,000
Other Liabilities	1,100,000
Central Service Center [Member]
Accrual For Environmental Loss Contingencies [Abstract]
Other current liabilities	0	0	5,000
Other non-current liabilities	424,000	495,000	501,000
Other Liabilities	400,000
Front Street [Member]
Accrual For Environmental Loss Contingencies [Abstract]
Other current liabilities	1,131,000	1,697,000	0
Other non-current liabilities	395,000	0	947,000
Other Liabilities	1,500,000
Other Environmental [Member]
Accrual For Environmental Loss Contingencies [Abstract]
Other current liabilities	0	0	0
Other non-current liabilities	$ 116,000	$ 120,000	$ 117,000