Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
INDEFINITE LIVED INTANGIBLE ASSETS:
Indefinite lived intangible assets	$ 1,545	$ 1,545
AMORTIZED INTANGIBLE ASSETS:
Gross Amount	25,384	25,384
Accumulated Amortization	(14,157)	(14,157)
Net Amount	11,227	11,227
Total intangible assets, Gross Amount	26,929	26,929
Total intangible assets, Net Amount	12,772	12,772
Acquired ICFAs
AMORTIZED INTANGIBLE ASSETS:
Gross Amount	17,978	17,978
Accumulated Amortization	(12,154)	(12,154)
Net Amount	5,824	5,824
Sonoran contract rights
AMORTIZED INTANGIBLE ASSETS:
Gross Amount	7,406	7,406
Accumulated Amortization	(2,003)	(2,003)
Net Amount	5,403	5,403
CP Water Certificate of Convenience & Necessity service area
INDEFINITE LIVED INTANGIBLE ASSETS:
Indefinite lived intangible assets	1,532	1,532
Intangible trademark
INDEFINITE LIVED INTANGIBLE ASSETS:
Indefinite lived intangible assets	$ 13	$ 13