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Business Description And Significant Accounting Policies: Allowance for Doubtful Accounts (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Accounts Receivable, Allowance for Credit Loss [Roll Forward]      
Accounts Receivable, Allowance for Credit Loss, Current $ 2,444 $ 3,209 $ 3,081
Additions Charged to Costs and Expenses 8,927 5,795 6,859
Recoveries and Other Additions 4,728 3,942 4,092
Write-offs and Other Deductions (9,096) (10,502) (10,823)
Accounts Receivable, Allowance for Credit Loss, Current 7,003 $ 2,444 $ 3,209
Potential economic impact of the COVID-19 pandemic      
Accounts Receivable, Allowance for Credit Loss [Roll Forward]      
Additions Charged to Costs and Expenses 3,300    
Accounts Receivable, Allowance for Credit Loss, Current $ 3,300