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Income Taxes: Carryforwards, State and Foreign Tax Credits (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Tax Credit Carryforward [Line Items]      
Income Tax Expense (Benefit) $ 32,918 $ 29,580 $ (23,667)
State and Local Jurisdiction      
Tax Credit Carryforward [Line Items]      
Tax Credit Carryforward, Valuation Allowance 12,800    
Income Tax Expense (Benefit) 1,300    
State and Local Jurisdiction | Investment Tax Credit Carryforward      
Tax Credit Carryforward [Line Items]      
Deferred Tax Assets, State Tax Credits 23,060    
State and Local Jurisdiction | Research Tax Credit Carryforward      
Tax Credit Carryforward [Line Items]      
Deferred Tax Assets, State Tax Credits $ 278