Commitments, Contingencies and Uncertainties (Costs Incurred To Comply With Federal Environment Statutes) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Site Contingency [Line Items]
Cost Related to Alleged Excess Emissions At Generating Station					$ 300,000
Reduction of Environmental Cost Recognized	100,000				600,000
Clean Air Act
Site Contingency [Line Items]
Environmental remediation expense	716,000	[1]	615,000	[1]	810,000	[1]
Clean Water Act
Site Contingency [Line Items]
Environmental remediation expense	$ 264,000	[2]	$ 178,000	[2]	$ 597,000	[2]

[1] Includes $0.3 million related to alleged excess emissions at the Rio Grande generating station discussed below for the twelve months ended December 31, 2009.

[2] 2011 excludes a reduction of approximately $0.1 million related to an adjustment for estimated remediation costs for Copper generating station. 2009 also excludes a reduction of $0.6 million related to an adjustment for estimated remediation costs for a property previously owned by the Company.