Commitments, Contingencies And Uncertainties (Costs Incurred To Comply With Federal Environment Statutes) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended			12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012		Sep. 30, 2011	Sep. 30, 2012		Sep. 30, 2011
Clean Air Act
Site Contingency [Line Items]
Environmental Remediation Expense	$ 86	$ 164	$ 509	[1]	$ 457	$ 768	[1]	$ 696
Clean Water Act
Site Contingency [Line Items]
Environmental Remediation Expense	89	63	190		172	282		196
Four Corners Generating Station
Site Contingency [Line Items]
Cost Related to Environmental Litigation at Generation Station			$ 200			$ 200

[1] Includes an accrual of $0.2 million, in the first quarter of 2012, related to Four Corners generating station discussed below.