REVENUES: Receivables and Allowance for Uncollectible Accounts (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 4,869	$ 5,034
Additions to the allowance	551	739
Write-offs, net of recoveries	(1,776)	(1,917)
Balance at end of period	$ 3,644	$ 3,856
Allowance for uncollectible accounts as a percentage of customer receivables	2.80%	3.30%