CONDENSED CONSOLIDATED STATEMENTS OF INCOME Unaudited - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Operating revenue	$ 126,111	$ 134,553
Operations:
Water production costs	45,592	47,606
Administrative and general	29,097	26,319
Other operations	17,821	17,640
Maintenance	6,455	5,439
Depreciation and amortization	22,368	20,715
Income tax (benefit) expense	(2,991)	294
Property and other taxes	7,293	6,704
Total operating (income) expenses	125,635	124,717
Net operating income	476	9,836
Other income and expenses:
Non-regulated revenue	4,901	4,419
Non-regulated expenses	(2,219)	(5,437)
Other components of net periodic benefit cost	(1,259)	(2,546)
Allowance for equity funds used during construction	1,533	911
Income tax (expense) benefit on other income and expenses	(828)	758
Net other income (loss)	2,128	(1,895)
Interest expense:
Interest expense	11,075	9,198
Allowance for borrowed funds used during construction	(831)	(495)
Net interest expense	10,244	8,703
Net loss	$ (7,640)	$ (762)
Loss per share:
Basic (in dollars per share)	$ (0.16)	$ (0.02)
Diluted (in dollars per share)	$ (0.16)	$ (0.02)
Weighted average shares outstanding:
Basic (in shares)	48,086	48,030
Diluted (in shares)	48,086	48,030