OTHER INCOME AND EXPENSES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Other income and expenses
Revenue from contracts with customers	$ 905,623	$ 790,334	$ 772,616
Loss (gain) from non-qualified benefit plan investments	(3,578)	(4,919)	7,161
Nonoperating expense	14,201	11,807	24,821
Revenue	20,628	18,509	21,276
Expense	14,201	11,807	24,821
Operating and maintenance revenue
Other income and expenses
Revenue from contracts with customers	13,818	12,499	12,860
Expense from contract with customer	12,289	10,786	11,959
Leases
Other income and expenses
Lease revenue	2,410	2,504	2,642
Lease expense	38	26	46
Design and construction
Other income and expenses
Revenue from contracts with customers	715	652	416
Expense from contract with customer	503	536	328
Meter reading and billing
Other income and expenses
Revenue from contracts with customers	48	198	534
Expense from contract with customer	0	2	123
Interest income
Other income and expenses
Interest income	1,260	303	177
Other non-regulated income and expenses
Other income and expenses
Nonoperating income	2,377	2,353	4,647
Nonoperating expense	$ 4,949	$ 5,376	$ 5,204