Summary Of Significant Accounting Policies (Goodwill) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Ecova [Member]	Dec. 31, 2010 Ecova [Member]	Dec. 31, 2011 Other [Member]	Dec. 31, 2010 Other [Member]	Dec. 31, 2009 Other [Member]	Dec. 31, 2011 Accumulated Impairment Losses [Member]	Dec. 31, 2010 Accumulated Impairment Losses [Member]	Dec. 31, 2009 Accumulated Impairment Losses [Member]
Balance at beginning	$ 25,935	$ 24,718	$ 20,689	$ 19,472	$ 12,979	$ 12,979	$ 12,979	$ (7,733)	$ (7,733)	$ (7,733)
Goodwill acquired during the year	12,933	1,113	12,933	1,113
Adjustments	177	104	177	104
Balance at ending	$ 39,045	$ 25,935	$ 33,799	$ 20,689	$ 12,979	$ 12,979	$ 12,979	$ (7,733)	$ (7,733)	$ (7,733)