CONDENSED CONSOLIDATED STATEMENTS OF LOSS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Operating revenue	$ 147,737	$ 125,563
Operations:
Water production costs	54,826	53,976
Administrative and general	30,369	29,680
Other operations	17,912	13,974
Maintenance	6,769	7,073
Depreciation and amortization	27,047	24,492
Income taxes	(101)	(3,937)
Property and other taxes	7,996	7,228
Total operating expenses	144,818	132,486
Net operating income	2,919	(6,923)
Other income and expenses:
Non-regulated revenue	5,572	3,827
Non-regulated expenses	(4,760)	(8,454)
Other components of net periodic benefit cost	2,979	(1,430)
Allowance for equity funds used during construction	544	1,614
Income tax (expense) benefit on other income and expenses	(358)	913
Net other income	3,977	(3,530)
Interest expense:
Interest expense	10,222	10,798
Allowance for borrowed funds used during construction	(294)	(944)
Net interest expense	9,928	9,854
Net income	$ (3,032)	$ (20,307)
Earnings per share:
Basic (in dollars per share)	$ (0.06)	$ (0.42)
Diluted (in dollars per share)	$ (0.06)	$ (0.42)
Weighted average shares outstanding:
Basic (in shares)	50,440	48,583
Diluted (in shares)	50,440	48,583