OTHER INCOME AND EXPENSES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Other income and expenses
Revenue from contracts with customers	$ 772,616	$ 765,704	$ 697,577
Loss (gain) from non-qualified benefit plan investments	7,161	(3,800)	(4,293)
Nonoperating expense	24,821	17,234	14,300
Revenue	21,276	22,761	16,922
Expense	24,821	17,234	14,300
Operating and maintenance revenue
Other income and expenses
Revenue from contracts with customers	12,860	16,276	11,481
Expense from contract with customer	11,959	16,344	13,551
Leases
Other income and expenses
Lease revenue	2,642	2,744	2,398
Lease expense	46	230	48
Design and construction
Other income and expenses
Revenue from contracts with customers	416	619	802
Expense from contract with customer	328	611	704
Meter reading and billing
Other income and expenses
Revenue from contracts with customers	534	495	458
Expense from contract with customer	123	79	109
Interest income
Other income and expenses
Interest income	177	171	52
Other non-regulated income and expenses
Other income and expenses
Nonoperating income	4,647	2,456	1,731
Nonoperating expense	$ 5,204	$ 3,770	$ 4,181