Federal Income Taxes: Reconciliation From Tax At the Statutory Rate to the Income Tax Provision (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Income Tax Disclosure [Abstract]      
Income tax expense at statutory rate $ 4,412 $ 4,917 $ 5,790
Tax exempt interest, net (103) (38) (8)
Change in valuation allowance 0 (112) 19
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount 0 (39) 0
Other, net (597) 159 55
Total income tax expense $ 3,712 $ 4,887 $ 5,856