OTHER INCOME AND EXPENSES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Other income and expenses
Revenue from contracts with customers	$ 963,695	$ 905,623	$ 790,334
Gain from non-qualified benefit plan investments	(3,884)	(3,578)	(4,919)
Other non-regulated expenses	14,649	14,201	11,807
Revenue	20,776	20,628	18,509
Expense	14,649	14,201	11,807
Contract operating and maintenance revenue
Other income and expenses
Revenue from contracts with customers	13,734	13,818	12,499
Expense from contract with customer	12,180	12,289	10,786
Leases
Other income and expenses
Lease revenue	2,334	2,410	2,504
Lease expense	47	38	26
Design and construction
Other income and expenses
Revenue from contracts with customers	468	715	652
Expense from contract with customer	342	503	536
Meter reading and billing
Other income and expenses
Revenue from contracts with customers	49	48	198
Expense from contract with customer	4	0	2
Interest income
Other income and expenses
Interest income	2,232	1,260	303
Other non-regulated income and expenses
Other income and expenses
Other non-regulated income	1,959	2,377	2,353
Other non-regulated expenses	$ 5,960	$ 4,949	$ 5,376