CONDENSED CONSOLIDATED STATEMENTS OF (LOSS) INCOME Unaudited - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Operating revenue	$ 132,247	$ 122,036
Operations:
Water production costs	47,606	42,068
Administrative and general	26,319	22,746
Other operations	17,640	16,124
Maintenance	5,439	6,112
Depreciation and amortization	20,715	19,201
Income taxes	(229)	(884)
Property and other taxes	6,704	6,116
Total operating expenses	124,194	111,483
Net operating income	8,053	10,553
Other income and expenses:
Non-regulated revenue	4,419	3,462
Non-regulated expenses	(5,437)	(2,054)
Other components of net periodic benefit cost	(2,546)	(2,503)
Allowance for equity funds used during construction	911	779
Income tax expense on other income and expenses	758	(889)
Net other income	(1,895)	(1,205)
Interest expense:
Interest expense	9,198	8,710
Allowance for borrowed funds used during construction	(495)	(494)
Net interest expense	8,703	8,216
Net income	$ (2,545)	$ 1,132
Earnings per share:
Basic (in dollars per share)	$ (0.05)	$ 0.02
Diluted (in dollars per share)	$ (0.05)	$ 0.02
Weighted average shares outstanding:
Basic (in shares)	48,030	47,984
Diluted (in shares)	48,030	47,984
Dividends declared per share of common stock (in dollars per share)	$ 0.1875	$ 0.1800