CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income Statement [Abstract]
Operating revenue	$ 800,590	$ 748,439	$ 670,363
Production Expenses:
Purchased water	126,343	158,568	135,982
Power	21,769	11,457	9,602
Groundwater extraction charges	112,076	73,146	62,980
Other production expenses	50,973	48,851	47,636
Total production expenses	311,161	292,022	256,200
Administrative and general	125,998	105,830	98,656
Maintenance	32,895	31,301	25,729
Property taxes and other non-income taxes	37,686	35,928	34,475
Depreciation and amortization	115,323	112,855	105,868
Total operating expense	623,063	577,936	520,928
Operating income	177,527	170,503	149,435
Other (expense) income:
Interest on long-term debt and other interest expense	(72,575)	(71,390)	(66,144)
Pension non-service credit (cost)	6,436	3,769	(1,230)
Other, net	3,545	55	8,882
Income before income taxes	114,933	102,937	90,943
Provision for income taxes	12,355	8,970	5,956
Net income	102,578	93,967	84,987
Other comprehensive income:
Unrealized (loss) gain on investment, net of taxes of $0 in 2025, $(163) in 2024 and $166 in 2023	0	(442)	530
Adjustment to pension benefit plans, net of taxes of $0 in 2025, $0 in 2024 and $80 in 2023	(493)	611	(216)
Comprehensive income	$ 102,085	$ 94,136	$ 85,301
Earnings per share
—Basic (in dollars per share)	$ 2.93	$ 2.87	$ 2.69
—Diluted (in dollars per share)	$ 2.92	$ 2.87	$ 2.68
Weighted average shares outstanding
—Basic (shares)	35,002,252	32,701,292	31,575,197
—Diluted (shares)	35,102,487	32,779,573	31,663,274