Segment Reporting Assets by Segment (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Total Plant and Other Investments	$ 454,305	$ 365,590
Other Assets	124,670	77,341
Assets	578,975	442,931
Water Activities [Member]
Segment Reporting Information [Line Items]
Total Plant and Other Investments	453,625	364,955
Other Assets	118,020	75,096
Services and Rentals and Real Estate Combine [Member]
Segment Reporting Information [Line Items]
Total Plant and Other Investments	680	635
Other Assets	$ 6,650	$ 2,245