Summary Of Significant Accounting Policies (Goodwill) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Balance at beginning	$ 39,045	$ 25,935
Goodwill acquired during the year	33,484	12,933
Adjustments	3,430	177
Balance at ending	75,959	39,045
Ecova [Member]
Balance at beginning	33,799	20,689
Goodwill acquired during the year	33,484	12,933
Adjustments	3,430	177
Balance at ending	70,713	33,799
Other [Member]
Balance at beginning	12,979	12,979
Goodwill acquired during the year	0	0
Adjustments	0	0
Balance at ending	12,979	12,979
Accumulated Impairment Losses [Member]
Balance at beginning	(7,733)	(7,733)
Goodwill acquired during the year	0	0
Adjustments	0	0
Balance at ending	$ (7,733)	$ (7,733)